Paper - The primordial cranium of miniopterus schreibersi at the 17 millimetre total length stage (1919)

From Embryology
Embryology - 27 Oct 2020    Facebook link Pinterest link Twitter link  Expand to Translate  
Google Translate - select your language from the list shown below (this will open a new external page)

العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)

Fawcett E. The primordial cranium of miniopterus schreibersi at the 17 millimetre total length stage. (1919) J Anat. 53(4): 315-350.37. PMID 17103873

Online Editor  
Mark Hill.jpg
This 1919 historic paper by Fawcett describes the embryonic skull of the common bent-wing bat miniopterus schreibersi. The bat common and scientific names honour Carl Franz Anton Ritter von Schreibers (1775–1852) an Austrian naturalist.



Modern Notes: bat | skull

Bat: Hendra Virus | Category:Bat
Bat Images: Craniofacial Development Carollia perspicillata Stage 10-13 | Stage 12-17 | Stage 18-23 | Miniopterus schreibersii fuliginosus Stage 13-17 | Limb Stage 13-17 | Limb Growth Stage 13-17 | Stage 18-23 | Hipposideros pratti Stage 11-22
Historic Embryology - Bat  
Fawcett E. The primordial cranium of miniopterus schreibersi at the 17 millimetre total length stage. (1919) J Anat. 53(4): 315-350.37. PMID 17103873


Head Links: Introduction | Medicine Lecture | Medicine Lab | Science Lecture | Lecture Movie | Science Lab | pharyngeal arch | Craniofacial Seminar | mouth | palate | tongue | placode | skull | neural crest | Head and Face Movies | head abnormalities | Category:Head
Historic Head Embryology  
1910 Skull | 1910 Skull Images | 1912 Nasolacrimal Duct | 1921 Human Brain Vascular | 1923 Head Subcutaneous Plexus | 1919 21mm Embryo Skull | 1920 Human Embryo Head Size | 1921 43 mm Fetal Skull | Historic Disclaimer
Historic Disclaimer - information about historic embryology pages 
Mark Hill.jpg
Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

The Primordial Cranium of Miniopterus schreibersi at the 17 millimetre Total Length Stage

Edward Fawcett
Edward Fawcett

By Professor Fawcett E. M.D., University of Bristol

  • The expenses of this research were defrayed by a grant from the University of Bristol Colston Research Society.

Introduction

The embryo from which the models about to be described were made I owe to the kindness of Prof. J. P. Hill. It had I think been fixed in picric acid, a fact which gave me much trouble afterwards. It was in a fairly advanced state of ossification which increased the difficulties of making the reconstructions although in some respects it added to their interest.

Miniopterus schreibersi belongs to one of the two genera of the miniopterine division of the family Vespertilionidae and according to Flower and Lydekker (1) is the best-known of the four species of Miniopterus. It is very widely distributed, being found almost everywhere throughout the tropical and warmer temperate regions of the eastern hemisphere; specimens from Germany, Madagascar, Japan and Australia differing in no appreciable respect from one another. ,

The head of the animal before sectioning is of a comparatively simple type more especially as concerns the nose which is quite free from the elaborate external nasal appendages of the Rhinolophidae, but when one examines the deeper lying chondrocranium one is at once struck with the great elaboration and complexity of the anterior parts of the nasal capsule. But as will be seen later they are mere elaborations of what seems to be a common plan in the construction of the anterior region of the nasal capsule, and in the solution of this question the modelling of older stages such as this is essential.

The head of this embryo was cut into serial sections of 154 thickness and the model was made at an enlargement of 66-6 diameters in order to provide wax plates of one millimetre in thickness. As some cartilaginous parts were in a comparatively advanced state of ossification considerable difficulty was experienced in determining how much was originally to be assigned to cartilage and how much to perichondrial ossification—and the limits of ossification were not at all easy to determine as regards the auditory capsule, for the main reason that owing to the whole of the picrie acid not having been thoroughly washed out of the tissues, false staining resulted, cartilage for example staining yellow instead of blue with Mallory’s stain, and the bones doing the same thing in several sections. Several slides of sections had in fact to be restained, and the result of restaining with Mallory’s stain is—at all events in my hands— very uncertain. Then, too, especially in the thin-walled cochlear capsule the cartilage before ossification seems to undergo a sort of fibrous degeneration and this staining in a somewhat tricky manner added to the difficulties!.

It will be seen as the parts are described in detail that whilst there are special modifications in certain parts the primordial cranium of Miniopterus follows pretty closely that of other mammals, and it certainly is of great interest.

Before entering into these details a short account of the conditions holding good for the adult cranium may be not out of place. According to Weber(2) on the skull in Microchiroptera the facial part is sometimes so shortened “dass die Gesichtsknocken darunter litten.”’ ‘Ihr Hirnschadel ist gleichfalls verkurzt, dabei aber verbreitert und abgerundet, mit Demarkation der darunterliegenden cerebellaren, cerebralen und olfaktorischen Hirnabteilung. Abgesehen von der Tatsache, das die Nahte der Schadelknocken, namentlich aber die Gesichts, bei Microchiroptera, friih verschmelzen, influenzierte auf deren Schidel unzweifelhaft die Gewohnheit, Insekten im Fluge zu haschen. Dies forderte eine weite Mundspalte und daneben ein kraftiges Gebiss, dementsprechend starke Ausbildung des Musc. temporalis und der mm. pterygoidei.... Den grossen Pterygoidmuskeln entsprechen nach hinten ausgedehnte Pterygoidei. Die Fossae pterygoideae dagegen sind klein....Das Foramen lacrimale liegt facial....Die Wand der Schadelhéhle wird namentlich durch die grossen Parietalia gebildet. Orbito- und Alisphenoid kénnen teilweise hautig bleiben, so dass das Foramen opticum alsdann der knéchernen Umrandung entbehrt. Das Petrosum....bei Microchiroptera ist das Knochengewebe so sparsam, dass das knécherne Labyrinth mit seinen halbzirkelférmigen Kandlen und mit der ' Cochlea deutlich zu Tage tritt. Letztere hat derartige Ausdehnung, dass dem Basioccipitale zwischen den beiderseitigen Cochleae nur beschrankter Raum eriibrigt. Bei Megachiroptera ist die Trommelhéhle nur hautig geschlossen, das Tympanicum schmal ringférmig, lose. Bei Microchiroptera soll es dagegen zu einer Bulla aufgeblasen sein die aber stets an die urspriingliche Ringform erinnert und wohl nie die ganze Trommelhéhle umwandent, auch liefert es keinen knéchernen dusseren Gehérgang. E. Blanchard und Maisonneuve erkannten jedoch bereits, dass die Bulla selbstandig entsteht und erst sekundar mit dem Tympanicum verschmilzt, das, wenn auch verbreitert, seine Ringform bewahrt....Der Gaumen der Microchiroptera aber liegt entweder in gewohnter Weise in der Flucht der Schadelachse oder er ist nach aufwarts gebogen. Begegnen sich die Intermaxillaria nicht in der Medianlinie ist der Gaumen nach vorn offen; er wird hier durch Knorpel erganzt der aber auch fehlen kann (Rhinolophidae Grosser). Auch die Ausdehnung des Gaumens nach hinten iiber die Zahnreihe hinaus ist eine verschiedene.

' 1 Thave since found that if the aniline blue of the stain be thoroughly removed by alcohol, restaining is simple and satisfactory. . Primordial Cranium of Miniopterus schreibersi = 317

Die Nasenhohle erfuhr Reduktion infolge des Gesichtsschadels, jedoch in verschiedenem Grade. Bei samtlichen erlitt das Nasoturbinale Riickgang, der fast zum Schwunde fiihren kann. Die Ethmoturbinalia sind gering an Zahl, aber noch in zwei Reihen angeordnet und gewunden (Vespertilionidae z. B.); sie scheinen aber bei Riickbildung der Intermaxillaria einfach zu werden und sich auf eine Reihe zu beschranken (H. Allen, Grosser). Dieser Riickschritt kann sich auch auf das Maxilloturbinale ausdehnen.

Am Unterkiefer ist der aufsteigende Ast meist niedrig, der Processus coronoideus meist breit fiir den Ansatz des starken Musc. temporalis, der Processus angularis sehr verschieden stark entwickelt; der Condylus mandibulae bei den Megachiroptera merklich verbreitert.”

THE PRIMORDIAL NEURAL CRANIUM

This, in accordance with the plan which I have adopted in previous com munications, is divisible into the following parts:

1. A central stem, to which are appended, at more or less constant positions,

2. Appendages to the central stem,

8. Lateral structures,

4, Commissures binding the central stem and the appendages together,

5. Commissures binding the lateral structures together,

6. Dorsal structures, viz. those which lie dorsal to the encephalon and form a cartilaginous roof to the cavum cranii.

1. Tue CenTRAL Stem (Pls. XIII, XIV).

The central stem stretches from the anterior margin of the foramen magnum to the top of the nose. It consists of the following parts. viz. from behind forwards: a pars chordalis, a pars trabecularis and a pars interorbito-nasalis. (It has been shown elsewhere on what grounds this mode of description is based.) With the exception of that part which is included within the nasal capsule, the central stem tends to be flattened from above downwards, the intra-nasal part being flattened from side to side.

Detailed Description of the Central Stem.

The pars chordalis is to a large extent ossified to form the basi-occipita] segment of the occipital bone, but anteriorly and postero-laterally it is still cartilaginous. In general form, as seen either from above or below, it is triangular in shape with the angles blunted.

Each postero-lateral or basal angle is delimitable by an imaginary line drawn through the anterior margin of the hypoglossal canal of its side. At this imaginary line each is continuous without histological difference into the exoccipital cartilage and from the anterior side of each basal angle a commissure ~-the chordo-eochlear commissure (Pls. XIII, XIV, XVII)—connects the pars chordalis with the hinder part of the cochlear capsule, This chordo-cochlear commissure shows some sign of ossification which is continuous with similar ossification of the cochlear capsule. The anterior basal angle is cartilaginous and fused without histological differentiation with the back of the pars trabecularis, only the site of emergence of the chorda dorsalis behind the crista transversa of the pars trabecularis giving any hint as to the anterior end of the pars chordalis. There are three borders, viz. a posterior and two lateral. The posterior border is concave backwards and forms the anterior margin of the foramen magnum. At its middle it is deeply indented forming the so-called incisura anterior. The indentation is caused by the dens of the axis vertebra. The anterior border towards its lateral extremity enters into the formation of the corresponding occipital condyle. Each lateral border is thin and for the most part consists of bone. It is separated from the cochlear capsule by a fissure which is the basi-cochlear fissure. This fissure extends from the chordo-cochlear commissure behind to the anterior trabeculo-cochlear commissure in front. It is therefore in direct continuity with the carotid canal. This confluence seems to result from the disappearance of a cartilaginous posterior trabeculo-cochlear commissure, fibrous traces of which persist. The upper or caval surface of the pars chordalis is triangular in form and very slightly concave from side to side (Pl. XIII). It is wide in its posterior half but narrow anteriorly where cartilaginous. Its narrowness recalls that seen in the corresponding region of the cat’s cranium and is clearly due to the large size of the cochlear capsules. The inferior surface (Pl. XIV) is convex from side to side, a fact marked bya keel-like antero-posterior ridge especially in its anterior half. The posterior half is much more gently concave from side to side.

There is no indication of any histological line of demarcation between the pars chordalis and the pars trabecularis, but it is not difficult to surmise where such demarcation ought to be.

The pars trabecularis (Pls. XIII, XIV) is readily recognised in the main by its being hollowed on its upper surface to lodge the pituitary body. It is of great length from behind forwards, recalling the condition observed in Microtus amphibius. Part of its apparent length is due to the failure of the post-optic limb of the ala orbitalis to meet the central stem as in the case of Microtus. Viewed from above it has a somewhat cruciform appearance (Pl. XIIT), the hind limb of the cross stretching backwards to fuse with the anterior end of the pars chordalis and being interrupted on its caval surface by a prominent crista transversa which bounds the pituitary fossa posteriorly. This hind limb is not ossified. The forelimb of the cross is ossified in its caudal half, but in front of this entirely cartilaginous. The lateral limbs of the cross represent the processus alares and each is ossified in direct continuity medially with the © centre of the cross which is ossified to form a single mass, the post-sphenoidal centre of ossification. At its outer end the processus alaris is continued anteriorly and posteriorly as cartilage, the posterior continuation is the anterior trabeculo-cochlear commissure which is directly fused with the cochlear capsule, whilst the anterior continuation is a somewhat small ala temporalis, Primordial Cranium of Miniopterus schreibersi 319.

which is notched on its lateral margin by the mandibular division of the fifth cranial nerve. It is not quite certain whether at an earlier stage the ala temporalis was formed independently of the processus alaris + ant. trabeculocochlear commissure but there does seem to be a junctional region at which the cartilage is of a younger type. Additionally it is bounded, laterally and anteriorly by the ossified membranous alisphenoid and along the anterior half of its medial edge it is in contact with the upper part of the pterygoid bone, which also supports it from below. The central part or body of the cross is of considerable size, flattened on its under aspect, but hollowed out cavally to lodge the pituitary body.

The pars interorbito-nasalis is of great length, longer in fact than the combined pars chordalis and pars trabecularis. In its posterior part it is flattened from above downwards and is directly fused with the ala hypochiasmata and with the pre-optic limb of the ala orbitalis on each side and this fusion greatly increases the apparent width of the interorbital part of this segment of the central stem. Its real width may be ascertained in the interval between the alae orbitales behind andthe hinder part of the nasal capsule infront. The nasal part of the pars interorbito-nasalis is the nasal septum which is deep posteriorly at the junction of the anterior two-thirds with the posterior third, and comparatively low in height anteriorly. As seen from the side it is almost triangular in outline, the base of the triangle being backwards towards the cavum cranii where it forms the crista galli whose free edge directed towards the cavum cranii is almost at right angles to the rest of the septum and whose dorsal angle is prolonged back under the interfrontal suture in the form of a long spur (Pl. XV). The further description of this region will be undertaken with that of the nasal capsule.

2, SrRucTURES APPENDED TO EACH SIDE OF THE CENTRALSTEM (Pls. XIII, XIV).

These structures which are paired are from behind forwards: (a) The exoccipital cartilage.

(b) The auditory capsule.

(c) The ala temporalis.

(d) The ala orbitalis.

(e) The lateral nasal capsule.

(a) The Exoccipital Cartilage (Pls. XIII, XIV, XVII).

Each exoccipital cartilage may be regarded as the postero-lateral continuation of the corresponding basal angle of the pars chordalis. In this instance each has commenced to ossify, a circumstance which for some reasons somewhat complicates matters and for others makes simple what might be somewhat difficult, more especially as the supraoccipital cartilage is almost wholly ossified. The site of commencement of the exoccipital cartilage is sufficiently indicated by a line drawn across the anterior edge of the hypoglossal canal. From this it passes backwards and outwards at first with a curved direction concave towards the foramen magnum of which it forms the anterior half of the lateral boundary. It presents to view two surfaces, viz. a caval directed upwards and medialwards towards the cavum cranii, and an extra-caval or inferior surface which is directed towards the neck. The margins may be desgribed as median and lateral.

We will examine the surfaces first.

The caval or superior surface (Pls. XIII, XVII) is of considerable size. At its commencement in front it is at first narrow from side to side and is notched by the hypoglossal canal which is completed in front by the pars chordalis. Speaking of the exoccipital as a separate entity this part appears to be connected with the pars chordalis by two prong-like projections which embrace between them the hypoglossal or twelfth cranial nerve here in two bundles, and the upper prong is connected with the pars cochlearis of the auditory capsule, by means of a commissure which is really the somewhat broad chordo-cochlear commissure which has extended beyond its usual limits to reach the exoccipital cartilage. The lower prong is the deeper of the two and helps to form at its under border the anterior part of the exoccipital condyle. Behind the site of off-springing of these prong-like boundaries of the hypoglossal canals the caval surface of the exoccipital cartilage increases in size mainly owing to its being prolonged under the canalicular part of the auditory capsule as the lamina alaris, forming a large grooved area here which lodges the lower part of the lateral sinus. This groove is overhung by the very prominent crus cominune of the confluent anterior and posterior semicircular canals and by its lateral edge this part of the caval surface of the exoccipital cartilage is confluent with the pars canalicularis of the auditory capsule. Traced in a forward direction the grooved part of the caval surface of the lamina alaris runs out as the upper surface of a tolerably well-marked processus paracondyloideus and a large foramen, the foramen jugulare intervenes between this and the overlying auditory capsule and is bounded medio-anteriorly by the chordocochlear commissure. This foramen jugulare is not continued backwards as a fissura supra-alaris as is the case in other animals described. This may however be a difference due to greater age. Behind the region of the auditory capsule the caval surface of the exoccipital cartilage becomes narrower and merges insensibly into that of the now ossified supraoccipital.

The nuchalor inferior surface of the exoccipital cartilage (Pl. XIV) resembles in general outline the caval surface, but differs in many details. It is concave laterally where it is continuous with the inferior surface of the processus paracondyloideus. It is convex towards its medial margin where it takes part in the formation of the occipital condyle.

As this surface of the exoccipital cartilage is traced backwards beyond the limits of the ossific centre mentioned it ultimately blends with the corresponding surface of the supraoccipital cartilage.

The processus paracondyloideus (P|. XIV) is of considerable size and placed under the anterior end of the posterior semicircular canal with whose under Primordial Cranium of Miniopterus schreibersi 321

surface it is directly confluent although a deep gap intervenes between the two, a gap which is however only visible from without (Pl. XV, text-fig. 1). This gap is the representative of the exoccipito-capsular fissure of other animals in which it is present.

The margins or borders of the exoccipital cartilage are median and lateral.

The lateral margin (Pls. XIII, XIV) when traced from before backwards, consists of first a part which, belonging to the upper margin of the hypoglossal canal, is fused with the chordo-cochlear commissure and through that with the pars cochlearis of the auditory capsule ; secondly a freeconcave part which forms the hinder and inferior margin of the foramen jugulare; beyond this it may be perhaps best described as being double-lipped, having a median lip fused with the pars canalicularis (posterior semi-circular canal) and crus commune of the auditory capsule along the whole length of its postero-inferior aspect, and a lateral lip which is free and extending back from the processus paracondyloideus forms the lower lip of the mouth of entrance to the representative of the exoccipito-capsular fissure (fig. 1).

The median boundary or border extends backwards first as the occipital condyle, then becomes suddenly prominent and sharp, due to the formation of a cap of articular cartilage here, after which it becomes less prominent and it ends finally by becoming confluent with the lower margin of the ossified supraoccipital (Pl. XIV). It forms the anterior half of the lateral margin of the foramen magnum. .

(b) The Auditory Capsule (Pls. XIII, XIV, XV, XVI, XVII).

The auditory capsule is remarkable in several respects---amongst which and perhaps most noticeable are the great prominences of its semicircular canals and the almost complete isolation of the anterior one. The lateral semicircular canal too forms a very marked prominence on the lateral aspect of the capsule (Pl. XV). The fossa musculi stapedii is of enormous size (Pl. XIV). The capsule is directly fused to a large part of the exoccipital cartilage, but the cochlear part of the capsule which is of large size is only in the most meagre fashion fused to the central stem.

The auditory capsule is divisible into the two following parts, viz. a hinder, the pars canalicularis, and an anterior, the pars cochlearis (Pl. XVII).

Of these two the hinder or pars canalicularis is the larger and as seen from without and below appears to be placed almost at right angles with the pars cochlearis. This rectangular form of the capsule as seen from the inferolateral aspect is very largely due to the great prominence of the lateral semicircular canal.

The capsule is moored to surrounding parts in the following way. Above, to the cartilaginous brim of the cranium through thelamina parietalis (Pl. XV), which starts from the fore-end of the anterio: semicircular canal, passes upwards to separate the supraoccipito-capsular fissure from the spheno-parietal fontanelle, Next it is moored to the opercular process of the supraoccipital cartilage by a supraoccipito-capsular commissure which attaches itself to the hinder end of the posterior semicircular canal just before that joins the crus commune. This commissure separates the supraoccipito-capsular fissure from the exoccipito-capsular fissure which is really open for a short distance here to transmit a small vein to the exterior. The pars canalicularis is fused to the whole median lip of the lateral border of the exoccipital by what may be called an exoccipito-capsular commissure which takes a large part in the formation of the sulcus which lodges the sinus venosus lateralis (fig. 1).

The pars cochlearis is remarkably free from attachment to neighbouring parts of the chondrocranium. It is fused to the postero-lateral angle of the pars chordalis of the central stem by a comparatively small commissure, the chordo-cochlear commissure (Pls. XIII, XIV, XVII), which separates the jugular foramen posteriorly from the basi-cochlear fissure anteriorly. It is fused directly to the pars trabecularis by the anterior trabeculo-cochlear commissure which is of small size, but at this stage there is no posterior trabeculo-cochlear eémmissure, that having apparently disappeared by absorption, and the carotid foramen is thus confluent with the basi-cochlear fissure. The detailed description of the auditory capsule may now be entered upon and the pars canalicularis will be dealt with first.

The pars canalicularis (Pls. XIII, XIV, XV, XVI, XVII) is as generally in mammals of the form of a three-sided pyramid whose base is placed forwards. Its surfaces may be described as lateral, supero-mesial or caval, infero-mesial and basal or lateral, four in all.

The lateral surface (Pls. XV, XVI) is wholly extra-caval and roughly triangular in form with its apex (cupola) directed backwards and partly hidden from view externally by the opercular process of the supraoccipital cartilage. It presents to view three borders which are, one superior, one inferior, and one basal.

The superior border or prominentia semicircularis anterior (Pl. XV), commences behind at the cupola and arches upwards and forwards then downwards and forwards to become confluent with the upper end of the basal border. At the site of confluence a swelling is found which is the commencement of the prominentia utriculo-ampullaris superior (Pl. XVII). If we regard the superior border as the anterior-semicircular canal then we have here one of the characteristic features of the group to which Miniopterus belongs, for this anterior semicircular canal is, save at its anterior and posterior extremities, absolutely isolated from the rest of the pars canalicularis, a large vacuity separating the two, and this large vacuity takes very largely the place of the fossa subarcuata anterior, and it owes its existence to the very large size of the floccular segment of the cerebellum (fig. 1). In Microtus amphibius which I described in Vol. 11 of this Journal at the 17-5 total length stage and which was almost as far advanced in development as this specimen of Miniopterus there is a very deep fossa subarcuata anterior whose floor is perforated to the exterior by a small foramen, but the flocculus does not rest in the fossa as in Primordial Cranium of Miniopterus schreibersi 323

Miniopterus, and the small foramen just mentioned is in striking contrast to the relatively enormous opening seen in Miniopterus. It may then be safely concluded that this vacuity which largely replaces the fossa subarcuata anterior is due to the large size of the flocculus of Miniopterus, and that this large sized flocculus is correlated with the habits of the bat.

The inferior border commences at the cupola posteriorly and passes downwards and forwards to become confluent with the lower end of the basal border. As it is caused by the posterior semicircular canal it may be called the prominentia semicircularis posterior (Pl. XV). It separates the lateral from the infero-mesial surface and at. its anterior extremity enlarges to form the commencement of the prominentia utriculo-ampullaris posterior (fig. 2). Between it and the underlying lateral margin of the exoccipital cartilage there is a deep fissure which is only at its hindmost part confluent with the cavum cranii and is the representative of the exoccipito-capsular fissure of those animals in which it exists. This fissure is shallow at its anterior end owing to the fact that the prominentia semicircularis posterior is more intimately tied to the processus paracondyloideus of the exoccipital cartilage by a ridge-like swelling of the commissura exoccipito-capsularis.

The anterior border (Pl. XV) commences above at the anterior end of the superior border or to be more precise perhaps, at the anterior end of the prominentia utriculo-ampullaris superior. It is hidden from view by the petrosquamous venous sinus (the intracranial part of the lateral jugular vein). It descends with a slight forward inclination and is indented by the crus breve of the incus cartilage to form a shallow fossa incudis. Below this the anterior or basal border rapidly projects forwards to culminate in the crista parotica to which is attached the cartilaginous styloid process (s‘ympano-hyae); from this projection the lower half of the anterfor border descends and recedes forming here the lateral wall of the fossa musculi stapedii, which is of very large size. The anterior border terminates below at the prominentia utriculoampullaris inferior.

The lateral surface is remarkable for two things, viz. the presence of a large vacuity which lies under the prominentia semicircularis anterior, and for the presence of an enormous prominentia semicircularis labialis (fig. 3) which runs almost vertically upwards close behind the anterior border. As it passes upwards it increases in prominence because it is here forming its ampullated anterior extremity. To the lateral surface immediately lateral to the cupola, the supraoccipito-capsular commissure is attached.

The medial or supero-medial surface (P]. XVII) is ovoidal in form, longer vertically than from before backwards.

It is bounded above by the prominentia semicircularis superior, above and anteriorly by the prominentia utriculo-ampullaris superior, behind by the downward continuation of the prominentia semicircularis anterior, below by the crus commune of the anterior and posterior semicircular canals, below and anteriorly by the hind wall of the vestibular segment of the pars cochlearis of the auditory capsule. These structures in the order mentioned complete the ovoidal boundary of the supero-medial surface of the pars canalicularis. Within the confines of this boundary the remainder of the supero-medial surface is sunk very deeply to form the fossa subarcuata anterior and at the bottom of the upper third or so of this fossa a large vacuity is met with which in the cartilaginous skull communicates with the exterior although with all the parts in position it is closed by membranous tissue and by the posterior inferior angle of the parietal bone. As will be seen from the accompanying drawing (fig. 1) this large fossa lodges the paraflocculus. The infero-mesial surface (fig. 1) is partly visible from the cavum cranii and partly so from the exterior. The two parts are separated from one another by the exoccipitocapsular commissure. The caval part of this surface forms the roof of what corresponds with the recessus supra-alaris in other animals, which lodges in the main the lower end of the lateral venous sinus, together with the exit parts of the ninth, tenth and eleventh cranial nerves. The extracaval part of the infero-mesial surface is somewhat concave, placed between the posterior semicircular canal above and externally and the exoccipito-capsular commissure medially (fig. 1). It is depressed between these structures to form a fossa subarcuata posterior, which is limited anteriorly by the prominentia utriculo-ampullaris inferior (not shown in plates).

The basal surface of the pars canalicularis is partly confluent with the vestibular segment of the pars cochlearis, i.e. in its medial half, whilst the lateral half or so is free, forming the cartilaginous posterior wall of the primary tympanum. It is bounded medially by the vestibular segment of the pars cochlearis, laterally by the boundary common to it and the anterior border of the lateral surface of the pars canalicularis. This common border has been described in connection with the lateral surface in question so it need not be further alluded to. From the uppermost part of the free part of the basal surface the tegmen tympani projects forwards and downwards with a curious sinuous course. It finally bends inwards towards the “cochlear” segment of the pars cochlearis and ends in a pointed extremity (Pl. XIII). The tegmen tympani is covered above, though a fairly considerable interval separates them, by the backward extension of the alisphenoid (Pls. XIII, XVII). More posteriorly the relation between the two becomes more intimate. On the medial side of its root commences above the tympanic segment of the sulcus facialis. When this sulcus is traced downwards it is found to become confluent with the sulcus which lodges the stapedius muscle and which is of enormous size (Pl. XIV).

The pars cochlearis (Pls. XIII, XIV, XVII) may be divided, following Voit—as I have done in respect to this region in other communications—into a “vestibular” and a “cochlear”? segment(3). It is of large size, and contains the membranous cochlear duct, the saccule, the utricle and the ampullae of the semicircular canals.

The whole pars cochlearis is directed towards the central stem and viewed from the front seems to run almost at right angles inwards from the pars Primordial Cranium of Miniopterus schreibersi 325

canalicularis. The apex of this region is directed forwards. Tothe pars cochlearis just above the apex or cupola of the cochlear segment of the pars cochlearis the anterior trabeculo-cochlear commissure is attached. The greater part of the pars cochlearis is seen in the adult animal with very much the same appearance as in the foetal state—there being practically no superadded bone.

We may now consider the segments of the pars cochlearis which it will be remembered are the vestibular and the cochlear.

The vestibular segment presents for examination a medial or caval, an inferior superior and an infero-lateral surface. . :

The medial or caval surface (Pl. XVII) is identified by the fact that it is perforated by two openings, one the foramen acusticum superius + foramen faciale, the other the foramen acusticum inferius. These two openings are separated from one another by a broad bar of cartilage which is the crista falciformis. The upper opening is single, that is, the facial canal and the foramen acusticum superius are confluent but the facial and superior vestibular nerves occupy the usual relative positions, that is, the facial nerve is the more medial.

The lower foramen or foramen acusticum inferius transmits the cochlear nerve and the inferior division of the vestibular. From the inferior division of the vestibular nerve a large branch is directed through a special foramen to the lower part of the saccule and the lower wall of this foramen is ossified. There is likewise a foramen singulare in the hinder wall of the foramen acusticum inferius to transmit the nerve to the ampulla of the posterior semicircular canal. There are no separate foramina in either cartilage or bone for the branches of the cochlear nerve at this stage. Both the foramen acusticum superius + facial canal, and the foramen acusticum inferius are sunk at the bottom of a very slight depression which is the meatus auditorius internus.

Above the foramen acusticum superius + foramen faciale-is a prominent commissura suprafacialis which is prolonged backwards and outwards to form a prominent crest (Pl. XVII). This afterwards becomes ossified and retains in that form practically the same form as in the cartilaginous condition. The whole bony auditory capsule which can readily be disarticulated resembles very closely the cartilaginous one and the semicircular canals appear much as in the usual carefully prepared article of commerce.

The inferior surface is convex from side to side and may be said to stretch inwards from the foramen rotundum (cochleae) to the medial margin of the foramen perilymphaticum which is thus to be regarded as forming a perforation in the inferior wall of the vestibular segment of the pars cochlearis. The foramen itself lies just above the foramen jugulare and cannot be seen in the plates. —

The infero-lateral surface forms part of the medial wall of the tympanic cavity (fig. 5). It shows from above downwards the sulcus facialis, which lies somewhat medial to and below the tegmen tympani; the foramen ovale (vestibuli), which is occupied by the foot of the stapes cartilage and below the foramen ovale, the foramen rotundum which is in the usual position.


The “cochlear” segment is of comparatively large size and exhibits on its anterior aspect the number of its coils as a well-marked sulcus septi spiralis is present. This appearance is fully maintained in the fully ossified condition. The apical region is placed forwards and there is attached to it the anterior chordo-cochlear commissure which at this stage appears to go backwards from the ala temporalis.

(c) The Ala temporalis (Pls. X1I1, XIV, XVII).

Only a small part of this cartilage remains unossified and it would be difficult to hazard a guess as to what its limits and extent are at an early stage. So far as can be seen it is in direct continuity posteriorly with the anterior chordo-cochlear commissure whilst mesially and posteriorly it is in direct contact with the ossified processus alaris of the pars trabecularis which is here ossified to form the os post-sphenoidale although there seems to be signs

. of an original separation between the two. At about the middle of its lateral edge the cartilaginous ala temporalis is notched by the mandibular division of the fifth cranial nerve. Good views of it are obtained by inspection of Plates XIII and XIV. In ‘Plate XIII, the investing covering of bone has been removed from the upper side, where it is seen to be bounded medially by the post-sphenoidal centre with perhaps processus alaris likewise bony, in front of which is the upper lamina of the pterygoid bone. Laterally and in front is seen the alisphenoid and at the expense of the latter chiefly the foramen ovale is seen bounded medially by cartilage. On the right side in Plate XIII all bone has been removed save that which may be processus alaris (if this ossify independently). It is to be noted that the anterior trabeculo-cochlear commissure is wossified at this stage.

(da) The Ala orbitalis (Pls. XIII, XIV, XV, XVI).

This resembles in many respects that of Microtus amphibius and chiefly because the post-optic limb of the ala fails to meet the upper aspect of the root of the ala hypochiasmata and so close in the foramen opticum. This foramen then is absent, is represented by a notch in the hinder border of the ala orbitalis which may be called the incisura optica (Pl. XIII), and the optic nerve passes through this notch to the orbit. This condition may be regarded as transitional between that of the marsupial in which the incisura is not even present (Dasyurus) and the higher mammals in which a complete foramen opticum is the rule. The main mass of the ala orbitalis is somewhat triangular in form having the apex directed towards the central stem with whose interorbito-nasal segment it is fused. This apical part represents only the pre-optic limb of the ala orbitalis. The base has’ projected forwards from its anterior basal angle its share of the spheno-ethmoidal commissure, which anteriorly having bounded on its lateral aspect the orbito-nasal fissure fuses with the backwardly directed process from the prominentia frontalis of the pars intermedia of the lateral nasal capsule. The posterior basal angle is continued Primordial Cranium of Miniopterus schreibersi 327

backwards into the orbito-parietal commissure. Both of these commissures are slender. The anterior border of the ala temporalis is sharp and forms the hinder boundary of the orbito-nasal fissure; the posterior border of the ala forms the anterior or superior border of the sphenoidal fissure which is here bounded posteriorly by the ossified alisphenoid.

The ocular muscles are the usual recti with a retractor bulbi and two obliques. All save the obliques take origin from the ala hypochiasmata. The superior oblique arises from the ala orbitalis behind the orbito-nasal fissure and some considerable distance from the incisura optica. The inferior oblique arises from the maxillary prominence of the pars intermedia of the nasal capsule immediately below the os lacrimale (Pl. XIV).

(e) The Lateral Nasal Capsule.

This at this stage is very completely chondrified, and is exceedingly complicated ; moreover it is of considerable length, but its detailed description will be reserved until later.

8. LATERAL StructTuREs (Pls. XIII, XIV, XV).

These paired structures are: (1) The supraoccipital cartilage. (2) The lamina parietalis (parietal plate). (8) The ala orbitalis.

(1) The supraoccipital cartilages are to a very large extent ossified, only the more anterior part remaining entirely cartilaginous, and fusion with the exoccipital cartilage below is so complete that it is not possible to define its lower extent with any certainty. From what remains of it however it would seem to have been of triangular form, with base forwards, and the upper basal angle is directly continuous by what I have elsewhere—Poecilophoca, p. 426— named a commissura supraoccipito parietalis, a slender commissure which forms the upper boundary of the supraoccipito-capsular fissure. The inferior basal angle is in part fused with the auditory capsule just lateral to the point where the posterior limb of the anterior semicircular canal blends with the corresponding limb of the posterior semicircular canal to form the crus commune, forming here a supraoccipito-capsular commissure. The apical region of the supraoccipital cartilage 1 is entirely ossified so that one cannot say what its earlier form was.

(2) The laminae parietales. Each lamina parietalis is of triangular form, attached by its apex to the anterior end of the corresponding anterior semicircular canal. This apex separates the supraoccipito-capsular fissure behind from the large spheno-parietal fontanelle in front. It is covered by the parietal bone which is separated from immediate contact with the apex by the vena capitis lateralis (Pl. XV) on its way from the cavum cranii to the post-glenoid foramen. The posterior basal angle is fused with the anterior basal angle of the supraoccipital cartilage to form the supraoccipito-parietal commissure. The anterior basal angle fuses with the posterior basal angle of the ala orbitalis to form the long and slender orbito-parietal commissure. Practically the whole of the lateral surface of the lamina parietalis is covered laterally by the parietal bone (Pls. XV, XVI).

(83) The alae orbitales have already been described.

The Lateral Commissures (Pls. XV, XIIT)

These from behind forwards are: (a) The supraoccipito-parietal. (b) The orbito-parietal.

(c) The spheno-ethmoidal.

The separate treatment of these structures is convenient because they help to form the rim or brim of the cavum cranii. Each is narrow and slender and the names given to each are topographical. Their precise limits and mode of formation cannot be given on account of the complete state of chondrification here presented. The following points are of interest in regard to them. The orbito-parietal commissures are entirely covered laterally by the parietal bone of their side, and the spheno-ethmoidal commissure is embraced on both its inner and outer sides by the frontal bone, because the orbital plate of that bone has begun to spread in as a covering bone towards the cribriform plate of the cartilaginous ethmoid (Pl. XIII). The part of the frontal bone which immediately covers the caval aspect of the spheno-ethmoidal commissure is very narrow, but the bone widens out having crossed the commissure and. almost completely blocks up the orbito-nasal fissure, only a small canal being left for transmission of the nasal nerve from the orbit to the region of the cribriform plate. This canal is naturally the anterior ethmoidal canal. The course of the nasal nerve was first explained by the late Prof. Gaupp, and I think this is a stage which would have greatly interested him. The sphenoethmoidal commissure is connected anteriorly with the frontal prominence of the pars intermedia of the nasal capsule as it always is.

As has been said, these commissures take part in the formation of the cranial rim or brim, which is formed on each side from behind forwards by the supraoccipital cartilage (here largely ossified), the supraoccipito-capsular comnuissure, the basal edge of the lamina parietalis, the orbito-parietal commissure, the spheno-ethmoidal commissure and the anterior curved border of the caval aspect of the lateral nasal capsule; to these may be added in the anterior median line, the prominent and backwardly curved crista galli.

4, DorsaL Commissures (Pls. XIII, XIV).

The only commissure which can be alluded to under this title is the tectum cranii posterius, but as it is here ossified to form the supraoccipital bone nothing more can be said about it. Primordial Cranium of Miniopterus schreibersi 329°

The Nasal Capsule (Pls. XIII, XIV, XV, XVI, XVIII, XIX).

This structure is of extraordinary interest and complexity especially anteriorly. It consists of a septum and two lateral appendages which are conveniently named the lateral nasal capsules. It is of large size and its total length is equal to that of the central stem behind it. In general shape as viewed from above (Pl. XIII), it is pyriform, the large end being posterior, and its greatest width is at the site of attachment of the inferior oblique muscles of the eyeball (Pl. XIV). As it is traced forwards it becomes laterally constricted at about the junction of the anterior fourth with the remainder; beyond, i.e. anterior to, this constriction, the capsule expands somewhat and in this region a wellmarked median sagittal sulcus dorsalis nasi becomes evident separating the two cupulae anteriores from one another.

The capsule as a whole may be regarded as presenting for examination from the exterior three surfaces, viz. a superior or dorsal, an inferior and a lateral surface.

The superior or dorsal surface (P1. XIIT) is large and as part of it is directed towards and forms part of the floor of the cavum cranii (the remainder being extra-caval), it may be divided into a caval or subcerebral and an extra-caval or precerebral part.

The caval surface will be described first.

The caval surface is of large size, ovoidal—very nearly circular—in form, and slightly compressed from above downwards so that its transverse is greater than its antero-posterior diameter. This part of the dorsal surface is so inclined as to be very nearly vertical, hence nearly at right angles to the extra-caval part. It is divisible into two symmetrical halves by a line drawn sagittally through the dorsal aspect of the septum nasi, which septum becomes evident along the anterior half of the median sagittal line drawn through this segment of the dorsal surface, and it rises cavally to end above in a large pointed and somewhat recurved crista galli (Pl. XV) which is covered by the meeting of the two frontal bones at the metopic suture.

Each half of the caval (subcerebral) surface is divisible into an anterior and a posterior part; of these two the posterior is flat and complete and passes without break of continuity medially into the dorsal part of the septum nasi. For this part I suggest the name pars imperforata. It is continuous laterally through the orbito-nasal fissure with the planum antorbitale of the lateral nasal capsule. In front of the pars imperforata, which may be regarded as having an anterior concave margin, is the anterior segment of the caval surface. At this stage the.pars imperforata is being covered by the orbital plate of the frontal bone and being therefore excluded from the cavum cranii. Over it, under the orbital plate of the frontal bone, the nasal nerve courses to reach the cavum before crossing the lamina cribrosa. This, nearly circular in form, is perforated by the roots of the olfactory nerve and may be called the pars, perforata. It is identical with the lamina cribrosa (cribriform plate).


The foramina in this region are divisible into at least two main groups, viz. a postero-median and an antero-lateral group, and an antero-posterior lamina of cartilage separates them. This corresponds with the crista intercribrosa of Voit. It differs only in its direction from that in the rabbit which Voit described and in Microtus described by myself. In the two latter there is crista intercribrosa (Pl. XIII) which runs from behind obliquely forwards and inwards towards the septum nasi. Here there is a lamina in place of a crest and it is directed parallel with the sagittal plane. It may be pedantic to describe it as the lamina intercribrosa, though it really is more than a crest. To its medial side the medial olfactory foramina are situated, and along its posterior edge numerous posterior foramina are met with which together with the median foramina constitute the postero-median group. Immediately in front of the most anterior median foramen a large circular foramen is met with. It transmits the nasal nerve to the nasal cavity. This nerve is of enormous size and retains its circular form for some time after it has entered the nasal cavity (fig. 10).

The extra-caval or precerebral part of the dorsa] surface of the nasal capsule is separated from the caval part by a sharp boundary caused by the almost rectangular inclination of the one to the other. It is wide posteriorly and divisible into two primary parts, viz. a posterior constituting about onethird of the whole, and a remaining anterior two-thirds.

The posterior third is separated from the anterior two-thirds by a somewhat deep sulcus which is the sulcus antero-lateralis (Pls. XITI, XV, XIX) and which is perforated at the site of junction of the dorsal with the lateral surface of the capsule by a very small foramen epiphaniale (Pl. XIX). This segment of the dorsal surface is the prominentia frontalis of the pars intermedia of the nasal capsule. It is overlapped by the frontal bone. It will be seen later that the prominentia frontalis is the outward expression of the recessus frontalis. Professor Terry(4) has in his careful and interesting study of the primordial cranium of the cat suggested that the foramen epiphaniale is the remnant of the fissure which separated the parieto-tectal from the paranasal cartilage of his terminology. That the nasal capsule does appear to develope in this way I believe to be true; it certainly is the case in Bos as the plate accompanying my communication on Erinaceus(5) shows and as Noordenbos(é) has seen, but it had not occurred to me to account for the foramen epiphaniale in the way Terry I think rightly does, and the suggestion may be extremely helpful in the understanding of this region.

The anterior two-thirds of the extra-caval or precerebral surface is divisible into approximately two halves, viz. a posterior and an anterior by means of the annular constriction previously alluded to, a constriction due possibly to the limitations imposed on peripheral expansion by the junctional regions of the frontal and premaxillary bones in this position. The hinder half of this segment is overlapped by the frontal bones to a considerable extent and they nearly meet in the middle line over it, but anteriorly they diverge from one another leaving a large angular gap between them which completely exposes Primordial Cranium of Miniopterus schreibersi 331

the dorsal aspect of the capsule to view (Pls. XIII, XVI). This part of the dorsal surface is slightly concave from side to side, but although separated from the lateral surface of the capsule by a rounded margin, the change from one surface to the other is unusually abrupt, giving a squareness to coronal sections of this region not commonly met with.

The anterior half of this segment of the dorsal surface, viz. that part in front of the annular constriction above mentioned is completely free and uncovered in any way by bone. I have been unable to identify a separate os nasale either in the specimen modelled or in the skull of an adult animal macerated from a specimen kindly given me by Prof. J. P. Hill. Nasalia are described by some authors as narrow splint-like bones lying medial to the frontalia, but I have been quite unable to identify them here and I scarcely think that they can have developed independently by this stagé and fused with the frontalia. As this part is traced forwards it appears to bifurcate into two hemispherical projections each of which is separated from its fellow by a well-marked sulcus dorsalis nasi (Pls. XIII, XVIII). These hemispherical projections are the cupulae nasi anteriores. Each at its basal part is in close relation with the upward and backwardly directed processus alaris inferior (Pls. XIII, XV, XVIII, XTX).

We may now turn our attention to the lateral wall of the nasal capsule as seen from the exterior (Pls. XV, XIX).

The external aspect of the lateral wall of the nasal capsule shows clear signs of demarcation into the usual three parts which are from behind forwards, the pars posterior or pars ethmoidalis, the pars intermedia or fronto-maxillaris and the pars anterior.

These parts are separated from one ‘another in much the same way as usual; thus, the pars posterior is separated from the pars intermedia by the sulcus postero-lateralis, which at the same time indicates the position of the first ethmo-turbinal in the interior. The pars intermedia is separated from the pars anterior by the sulcus antero-lateralis.

Of these parts the pars posterior is the smallest, the pars intermedia -the deepest, and the pars anterior the longest from before backwards.

The pars posterior is directed downwards and backwards from the pars intermedia. It is continuous through the orbito-nasal fissure with the pars imperforata of the caval segment of the dorsal part of the nasal capsule. Laterally it is directed towards the eyeball, so this part may be spoken of as the planum antorbitale. Its hindmost part is incomplete so there is no cartilaginous cupula posterior and, as viewed from the side, a vacuity takes the place of the cupula which is bounded below by a short backwardly directed process which bears some resemblance to the processus maxillaris posterior of the reptilian nasal capsule. This process is covered by the lamina perpendicularis of the os palatinum. It will be seen later that the absence of a true cupula nasi posterior leads to absence of the lamina transversalis posterior from the solum nasi.


The pars intermedia is the deepest part of the lateral aspect of the nasal capsule and is isolated by the antero-lateral and postero-lateral sulci. It is divisible into at least two parts, viz. a superior and an inferior. The superior part projects as the prominentia frontalis, of which a part has already been seen from above. The inferior part is directed towards the maxilla and from it there projects a small elevation which is the processus maxillaris anterior. From the most lateral part of the prominentia maxillaris the inferior oblique muscle takes origin, immediately above which lies the small perforated os lacrimale, with the naso-lacrimal duct passing forwards through it. Towards the lower edge of the maxillary prominence of the pars intermedia a longitudinal ridge is met with which can be traced from the processus maxillaris anterior to the processus maxillaris posterior. This ridge bounds laterally a sulcus whose inner margin is free and forms the hinder part of the lower edge of the maxillo-turbinal. The sulcus in question is caused by the mucosa of the nasal passage turning outwards and upwards below the maxillo-turbinal, which is of comparatively small size.

The pars anterior as viewed from the lateral aspect is long from before backwards, narrow from above downwards, and narrower in front than behind. It is somewhat quadrilateral in form with the base backwards wider behind than in front. It reaches from the antero-lateral sulcus behind to the lateral. margin of the anterior narial aperture in front. The upper border is rounded and through it this aspect is continuous with the dorsal aspect. of the capsule. The inferior border is sharp and divisible.

We may now consider the floor of the nasal capsule or solum nasi.

The solum nasi is incomplete, but what it lacks is fully compensated for by its complexity. It-may be said to consist of from before backwards, the following structures, viz. the ali-cupular commissure, the medial part of the processus alaris inferior, the lamina transversalis anterior, the anterior paraseptal cartilage, the posterior lamina of the cartilage of the naso-palatine duct, and finally the posterior paraseptal cartilage.

The ali-cupular commissure represents a part of the incomplete ring-like base of the cupula anterior of the capsule. It stretches from the medial wall of the anterior nasal aperture with a curved course, concave upwards to fuse with the middle of the anterior border of the processus alaris nasi inferior. It is separated from the processus lateralis ventralis of the septum nasi by a vacuity over which lies the nasal mucosa.

The medial part of the processus alaris inferior projects medially and backwards on the lateral side of the vacuity just mentioned and finally ends as a lacrimal spur on the outer side of the fissure through which the nasolacrimal duct enters the interior of the nasal capsule, and on the outer side too, of the lamina transversalis anterior.

_ The lamina transversalis anterior. This is a very curious structure and not at all easy to describe. On the whole one may perhaps describe it best as a somewhat triangular plate whose anterior and posterior sides are free, and Primordial Cranium of Miniopterus schreibersi 333

whose base is directed upwards towards the lower margin of the lateral wall of the nasal under cover of the naso-lacrimal duct over which it fuses with the lower border of the said lateral wall. The length of the line of fusion is smaller than the total length of the base of the lamina so that a small incisura post-transversalis and a small incisura pre-transversalis separate the base in part from the lower margin of the lateral wall of the nasal capsule. Through this anterior incisure the naso-lacrimal duct passes into the interior of the nose, and the outer side of the incisure is covered by the lacrimal spur of the processus alaris nasi inferior. On account of the shortness of-the basal attachment when compared with the total length of the basal border of the lamina I have marked this attachment on Plates XIV and XIX as the superior process of the lamina-transversalis anterior. It is the part which is also bent upwards as the atrio-turbinal. N.B. The indicating line in the plates has been carried too far forwards; it actually points to the lacrimal spur of the processus alaris nasi inferior.

':: The anterior basal angle of the lamina transversalis anterior is prolonged forwards as a long slender process as far as the processus lateralis ventralis, but it does not fuse with that structure. To this process I have given the name processus anterior of the lamina transversalis. It lies below the septum nasi and is separated from it by a downward projection of the nasal mucosa.

The apical part of the lamina transversalis anterior is twisted at right angles to the main mass (whose surfaces are infero-lateral, and supero-medial) so that its surfaces are fore and aft. This apical region is connected below with the anterior paraseptal cartilage medially and with the cartilage of the nasopalatine duct laterally.

The surfaces of the main mass of the lamina transversalis anterior are infero-lateral and supero-medial, but the whole direction of this part of the lamina is nearly vertical; by its supero-medial surface it is in relation with the nasal-mucosa, and by its infero-lateral surface it is in relation with that part of the os incisivum which forms the medial wall of the first incisor tooth socket. The apical region whose surfaces are twisted fore and aft, is in relation by its anterior surface with the commencement of the paraseptal process of the os incisivum which sweeps outward in front of this region (fig. 14) to later pass backwards on the medial side of the anterior paraseptal cartilage, and terminate a little distance in front of the vomer. Immediately behind the continuity of the apical region of the lamina transversalis anterior with the anterior paraseptal cartilage the duct of the organ of Jacobson turns upwards and outwards in a tunnel (fig. 9) of the latter to join the naso-palatine duct (fig. 10).

The anterior paraseptal cartilage (Pls. XIV, XV, XVIII, XIX, figs. 8, 9, 10, 11) is large and complex. Its large size corresponds with the large size of the organ of Jacobson which is lodged in its lateral concavity. Its description may commence for convenience at its posterior extremity which is placed at a point half-way along the infero-lateral border of the septum nasi.


The cartilage commencing in a pointed posterior extremity soon becomes of a plate line form with long axis directed almost vertically. This form it retains until the organ of Jacobson is reached where this plate becomes curved with its concavity outwards and the organ is lodged in the concavity, and as a consequence the plate may be regarded as consisting of a medial and an inferolateral wing. This condition (fig. 8) is maintained for the greater part of the . extent of the cartilage in a forward direction. On nearing the lamina transversalis the medial and infero-lateral wings of the plate fold together around the commencement of the duct of the organ of Jacobson so that it comes to lie in a tunnel (fig. 9), from which it soon emerges in an upward and outward direction in order to join the naso-palatine duct (fig. 10). The anterior paraseptal cartilage now by means of its medial limb becomes fused with the apical region of the lamina transversalis anterior (fig. 11) and- from this region runs forwards in confluence with the anterior process of the cartilage of the nasopalatine duct, forming with the latter a curved hood-like cartilage which is continued as far forwards as the processus lateralis ventralis. This curved cartilage lies over the anterior part of the naso-palatine duct (figs. 10, 11). In front of the junction between the medial lamella of the anterior paraseptal cartilage with the apical region of the lamina transversalis anterior, the root of the paraseptal process of the os incisivum turns inwards to run backwards along the medial side of the medial lamella of the anterior paraseptal cartilage (figs. 8, 9, 10, 11).

The cartilage of the naso-palatine duct is of large size and great complexity. It may be regarded as consisting of a central part, attached at its upper aspect to the more lateral part of the apical region of the lamina transversalis anterior, and of two processes, one anterior, the other posterior. The central part overhangs the site of junction of the organ of Jacobson with the naso-palatine duct. The posterior process passes backwards from this region in the form of a rapidly broadening lamella which at first is placed almost horizontally under the infero-lateral lamella of the anterior paraseptal cartilage from which it is separated by the naso-palatine duct (fig. 10). At about the middle of its course it attains its maximum width, still supporting what may be termed the aditus of the naso-palatine duct, then it begins to narrow and it ends posteriorly opposite the level of the middle of the anterior paraseptal cartilage, here supporting that part of the nasal mucosa which projects down below the lower margin of the lateral wall of the nasal capsule (fig. 8).

The anterior process commences at the central part, in direct continuity with the posterior process (Pl. XVIII); it is fused at first with the medial limb of the anterior paraseptal cartilage, the two forming the curved hood-like cartilage which overhangs the forward continuation of the naso-palatine duct (fig. 11). After that duct becomes confluent with the epithelium of the mouth, this anterior process is continued forwards as a somewhat slender rod of cartilage oval in section with long axis transverse to a point below the processus lateralis ventralis of the septum nasi (fig. 15). Between the anterior processes of the Primordial Cranium of Miniopterus schreibersi 335

two sides a dumb-bell shaped cartilage, the cartilage of the papilla palatina, is placed (fig. 12).

The posterior paraseptal cartilage is the forward prolongation of the inferomedial wall of the post part of the nasal capsule. The lamina transversalis posterior whose inner basal angle generally gives origin to the posterior paraseptal cartilage being in this instance absent. It is of considerable length and passes forwards alongside the infero-lateral border of the septum nasi separated from it by the corresponding lamella of the vomer (Pl. XIV).

The interior of the nasal capsule may now be considered.

The septal wall is low posteriorly but rapidly increases in depth, entirely by increase towards its upper end, the lower edge remaining constant. The highest part of the septal wall is that which culminates as the crista galli which, as already pointed out, is of large size, pointed at its extremity which is somewhat curved backwards. All the part of the septal wall posterior to the spring of the crista galli is subcerebral (subcaval); the remainder gradually falls in height at the expense of the upper part. At the anterior end this wall is everted partly as the processus lateralis ventralis, partly as the medial part of the cupola nasi anterius. There is no internarial foramen in the septum.

The lateral wall of the nasal cavity shows the three usual parts, viz. the pars anterior, pars intermedia and, the pars posterior.

The first is separated from the second by a somewhat faintly expressed crista semicircularis, the second from the last by the root of attachment of the first primary ethmo-turbinal.

There is little to be said concerning the internal surface of the pars anterior. No sign of a cartilaginous naso-turbinal is visible although a swelling of the mucous membrane hints at the possibility of there being such at a later date.

The pars intermedia is divisible into an upper and lower recess, both of which are continuous over the lower end of the crista semicircularis. The upper recess is the recessus frontalis, the lower is the recessus maxillaris. The upper or frontal recess receives several branches of the olfactory nerve through ‘foramina in the antero-lateral part of the lamina cribrosa which forms its roof. It is to a large extent shut off from the recessus maxillaris by the first ethmo-turbinal which forms a considerable part of its floor.

The recessus mavillaris is of large antero-posterior extent and contains in its antero-lateral part the lateral nasal gland so that it almost might be termed the recessus’ maxillo-glandularis. It is confluent above and in front of the first ethmo-turbinal with the recessus frontalis. Anteriorly it is continued into the cavity of the pars anterior, whilst it is overhung to a large extent by the first primary ethmo-turbinal. It opens out behind directly into the ductus naso-pharyngeus as the apex of the cupular region is awanting.

The pars posterior is small, deficient below and behind. It persists dorsally as the lamina imperforata and medially as the posterior paraseptal cartilage. It receives numerous branches of the olfactory nerve through the post group of postero-median foramina which descend along the nasal surface of the lamina imperforata. It is limited antero-laterally by the first primary ethmoturbinal which separates it from the pars intermedia. Its interior is complicated by two turbinals which project sagittally from the lamina imperforata. These are the second and third primary ethmo-turbinals and the third is about half the size of the second. The second is less than half the size of the first.

The anterior narial aperture may now be considered.

The aperture consists of an anterior and a lateral part. As a consequence the cupula anterior is deficient anteriorly and laterally, and is represented only by an incomplete ring-like base open outwards. The component parts of this incomplete ring are, above and supero-laterally, the tectum nasi and the lateral wall, terminating in a processus alaris nasi superior, respectively. Medially is the corresponding lamella of bifurcation of the septum, inferiorly the ali-cupular commissure, and infero-laterally the processus alaris nasi inferior. The lateral segment of the anterior narial aperture is directed outwards and upwards along the processus alaris nasi inferior, and bounded above by the processus alaris nasi superior. Posteriorly at its commencement it is bounded by the anterior border of the lateral wall of the nasal capsule which is bent inwards by the outgoing mucous membrane and the maximal inbending may be spoken of as a margino-turbinale since it supports from below a considerable mucous turbinal which projects into the interior of the nose (Pl. XVIII and fig. 15). This turbinal is in line with the atrio-turbinal caused by the inflexion of the superior process of the lamina transversalis anterior and that in turn is in line-with the maxillo-turbinal. The mode of formation of this region is best understood after reading the account of the nasal capsule of Tatusia novemcincta which follows this communication.

The processus alaris nasi inferius is of very large size. It springs from the lower part of the anterior border of the lateral wall of the nasal capsule and runs at first outwards with upper concave surface and lower convex aspect. It then twists somewhat on itself so that its upper surface becomes first medial then anterior, its lower surface thus being first lateral then posterior; finally contouring the lateral aspect of the nasal capsule it ends freely in a sharp point. It sends backwards from its root a small angular spur which projects over the naso-lacrimal duct where that is entering the naso-lacrimal fissure, and below this overlaps the outer surface of the lamina transversalis anterior just above and behind the root of the processus anterior of that cartilage (Pl. XVIII, fig. 13). The processus alaris nasi inferior is joined not far from the middle of its anterior border by the ali-cupular commissure (PI. XVIII), which ties it to the septum nasi through the intermediation of the medial part of the ring-line base of the cupula nasi anterius.

Before leaving the subject of the nasal capsule one may allude, and with pleasure, to the work of Terry on the subject in his communication on the primordial cranium of the cat. Working with van Wighe’s methylene blue method he has been able to show at the 18-20 mm. stage that the lateral wall Primordial Cranium of Miniopterus schreibersi 337

of the nasal capsule is laid down in three segments, which correspond very closely with the three segments already described here. These segments he describes as parieto-tectal which corresponds with the pars anterior, a part which may or may not be an outgrowth of the septum, another segment which he calls the paranasal cartilage developed independently is separated in front by a fissure which becomes the foramen epiphaniale when for the most part closed. The paranasal cartilage always gives attachment to the max. obliquus inferior oculi and corresponds with the pars intermedia; the hindmost segment, which he calls the lamina antorbitalis, corresponds with the pars posterior. The mutually inrolled approximated edges of the two anterior segments produce the crista semicircularis thus: the crista semicircularis is formed by the anterior edge of the paries nasi and the posterior edge of the pars parietotectalis. There is I think évery reason to believe that Terry is right, and his observation and interpretation of the facts are most helpful in the solution of a previously very difficult point. We may now pass to the consideration of the visceral cartilages.

Tue CARTILAGES OF THE VISCERAL ARcHES (Pls. XV, XVI).

The cartilaginous skeleton of the first visceral or mandibular arch are three in number, viz. from behind forwards: the incus cartilage, the malleus cartilage and Meckel’s cartilage.

The incus cartilage gives one the impression of being somewhat small. It shows the usual parts and so far as I can see has the usual relations. Its crus breve rests in a small fossa incudis placed some distance above the upper end of the root of the crista parotica. The whole cartilage is overhung by the vena capitis lateralis on its forward course to the post-glenoid region. The crus longum articulates with the head of the stapes cartilage in the usual way.

The malleus cartilage strikes one as being very large, the head and neck especially so. A well-marked crista mallei descends as a curved ridge concave backwards just in front of the incus malleus joint. The manubrium is short and directed inwards almost at right angles to the rest of the cartilage. Ossification has commenced in the head of the cartilage.

From the front of the head the next cartilage projects forwards. Meckel’s cartilage is long, comparatively slender, and cylindrical. It passes forwards and gently downwards, gradually converging on its fellow. A short distance behind the mental foramen it sinks into the mandible to again emerge not far from the anterior end of the bone after which it unites with its fellow. Just in front of the head of the malleus cartilage a long goniale covers the under aspect of Meckel’s cartilage.

The cartilages derived from the second visceral arch are the stapes and the processus styloideus or Reichert’s cartilage. The stapes cartilage is much of the usual type but has an enormous stapedius muscle inserted into it. It is perforated by a tolerably large stapedial artery which is larger than the onward continuation of the internal carotid artery from which it is derived.


Reichert’s cartilage is of considerable length. It starts as the direct continuation of the apex of the crista parotica and descends almost parallel with the neck of the malleus cartilage. It now changes its direction, passing forwards and somewhat inwards with a marked concavity upwards; next it arches forwards and inwards, then downwards, and comes to an end in a pointed extremity just behind the junction of the corpus hyale with the thyro-hyal— for a considerable stretch in front and behind its middle the cartilage is ossified.

The cartilage of the third visceral arch, namely the thyro-hyal, is of large size, commencing behind in a somewhat inbent pointed extremity. It curves outwards for a short distance and gives off a large descending process, after which it rapidly narrows. It runs into the lateral angle of the corpus hyale without any histological line of demarcation. The corpus hyale or 1st basi-branchial is of a very ordinary type and much resembles that of man in form. ,

In the model it lies across the front of the thyroid cartilage opposite the middle of the latter.

The cartilage of the fourth visceral arch is represented by the thyroid’ cartilage, which is of large size especially from before backwards. It consists of two alae which are at this stage completely fused in the middle line. Each ala commences behind at a preposterior border whose lower angle of junction with the superior border of the ala is prolonged downwards as a curved articular bar to articulate with the cricoid cartilage and from the lateral aspect of the junction of this inferior cornu or articular process a strong short muscular process projects. A superior cornu is developed at the usual site and is in direct cartilaginous continuity with the posterior end of the thyro-hyal. At the symphyseal region of the two alae in front no pomum Adami is de . veloped which is the usual arrangement in the lower mammals. From the back of the upper part of the symphyseal region a small spur of, cartilage pro- . jects in a backward direction. ,

The cartilages of the fifth visceral arch, viz. the cricoid and the arytenoids, are of large size, but do not present anything much out of the common in form. From the antero-lateral part of the ring of the cricoid two large muscular processes project directly outwards. The arytenoid cartilages are well developed and each of their recognised and usually described parts is well developed.

The whole larynx gives one the impression of being somewhat disproportionally large in comparison with the rest of the cranium.

THE OssEous SKELETON (Pls. XIII, XIV, XV, XVI, XVII, XVIII, XIX).

Both ecto-chondral and ento-chondral bones are met with, and the former are in a high degree of development. ,

So far as can be ascertained no separate nasalia are present.

The os frontale is of large size extending forwards over the nasal capsule, hiding from view the frontal prominence of the pars intermedia, then extending Primordial Cranium of Miniopterus schreibersi 339

as a long somewhat triangular process over the posterior half or so of the pars anterior, articulating as it goes along with the maxilla and the premaxilla. The medial margin of the anterior nasal process rapidly cuts away as it is traced forwards, so that when the two frontalia are viewed together in the adult a large nasal notch appears between them, and the same would hold good in this case had the bones been modelled on both sides; through this nasal notch the cartilaginous nasal capsule projects in a forward direction. Behind the extra-caval part of the nasal capsule the frontal bone rapidly expands to form a large curved plate which articulates in a metopic suture with its fellows of the opposite side and posteriorly is overlapped by the anterior edge of the parietale. This plate when traced downwards covers on its lateral aspect the ala orbitalis and the spheno-ethmoidal commissure, but it also sends medial to the latter a narrow piece which on leaving the commissure expands to block up the orbito-nasal fissure save for a small opening the anterior ethmoidal canal through which the nasal nerve passes. This orbital plate of the os frontale then covers a considerable part of the lamina imperforata of the pars posterior of the nasal capsule. There is no sign either of a supraorbital, crest or of a post-orbital process.

The os parietale is of very large size and of quadrilateral outline. It forms a covering bone to the hinder part of the ala orbitalis, to the orbito-parietal commissure, the lamina parietalis, the supraoccipito-parietal commissure and lies lateral too to the anterior semicircular canal as well as the subarcuate vacuity described in connection with the auditory capsule. It also blocks up the whole of the lateral part of the sphero-parietal fontanelle below the level of the orbito-parietal commissure.

Anteriorly the parietal bone overlaps the hinder edge of the frontal, but medial to the eyeball the ala orbitalis of that position is left uncovered and to this area the superior oblique muscle of the eyeball is attached. By its anterior inferior angle the parietal articulates with the alisphenoid whilst along a considerable part of the infero-lateral splay on its inferior border it is overlapped by the squamosal. The posterior part of the inferior border has no bone to articulate with, and lies against the lateral aspect of the pars canalicularis of the auditory capsule. The posterior border overlaps and articulates with the large interparietale. The medial border forms by articulating with that of its fellow the saggittal suture.

The interparietale (Pl. XVI) is a large bone, and so far as can be seen is of membranous origin. It is triangular in shape, its base overlapping the supraoccipital and near the anterior basal angle it overlaps to a slight extent the supraoccipital cartilage. Its anterior border is overlapped by the posterior edge of the parietal bone. Its medial border is slightly overlapped by that of its fellow of the opposite side. In the adult skull I can see no trace of a separate interparietale. ’

The incisivum or premazilla (Pl. XVI) is a quite considerable bone lodging two incisor teeth which are lodged in well-formed tooth sockets. From the tooth-bearing mass it sends upwards and backwards into the angle between the nasal process of the frontal bone and the nasal or frontal process of the maxilla a frontal process of acute angular form which fills up the gap between frontale and maxilla. The body or tooth-bearing segment of the bone lies mainly between the annular constriction of the nasal capsule and the cartilage of the naso-palatine duct. From the medial side of this mass there passes inwards in front of the stalk connecting the lamina transversalis anterior with the anterior paraseptal cartilage and the cartilage of the naso-palatine duct a paraseptal process (Pls. XIV, XVIII, fig. 10) which bends backwards on the medial side of the anterior paraseptal cartilage in the usual way. There is no sign of any separation between this process and the rest of the incisivum such as Broom describes in the adult. I have no means of knowing whether this paraseptal process ossifies independently. It terminates posteriorly in just front of the anterior extremity of the vomer. A true palatine process of the premaxilla is absent at this stage, evidently because of the large size of the enterior paraseptal cartilage and of the cartilage of the naso-palatine duct which both project through an enormous gap between the premaxilla and the palatine process of the maxilla. This deficiency of a palatine process seems to hold good in the adult.

The maztlla (Pl. XVI) is of large size and consists of the usual parts. At this stage of development it consists of a body perforated by a comparatively large infraorbital canal for the transmission of a large infraorbital nerve; from this border there projects up over the hinder part of the lateral wall of the pars anterior of the nasal capsule a large plate-like frontal process which articulates in front with the incisivum, above with the nasal process of the frontal bone, but behind is for the most part free, an angular gap separating it from the orbital part of the frontal bone, a gap which is occupied by the maxillary prominence of the pars intermedia of the nasal capsule. At the lower part of the posterior margin of this nasal process of the maxilla the os lacrimale is found and is of annular form.

From the lower part as well as the posterior part of the body there projects downwards and backwards an external alveolar process which with the inner alveolar process derived from the palatine process completes the sockets for the canine, first and second premolar teeth. These sockets are at this stage complete, and the septa between them appear to be mainly formed at the expense of the outer alveolar wall. The outer alveolar wall behind the second premolar socket is formed by the zygomatic (malar) process of the maxilla, which projects backwards as a huge pointed process below the eyeball to come into articulation vertically below the hinder margin of that structure with the comparatively small slender zygomaticum (malar), which overlaps the apex of the pointed posterior end of the zygomatic process of the maxilla. This zygomatic process forms the outer alveolar wall of the sockets-to-be of the three molar teeth. There is at this time no roof to these sockets nor is there any inner wall more than the outer margin of the palatine process of the maxilla. Primordial Cranium of Miniopterus schreibersi 341

The tooth-sockets of the aforesaid teeth are therefore in open communication with the orbital cavity in the model. The palatine process is a large platelike structure projected inwards from the body of the maxilla, i.e. from that part bearing more especially at this stage the sockets for the canine and premolar teeth. It is nearly square in form, with a slightly concave anterior margin which bounds posteriorly the large gap between it and the incisivum which transmits the cartilage of the naso-palatine duct and a considerable part of the anterior paraseptal cartilage. Its medial border anteriorly comes into contact with the vomer which it to a slight extent underlaps; more posteriorly this border recedes from the vomer somewhat so that a small fissure intervenes between the two. The posterior border articulates with the palatine process of the palatine bone in its whole length and from the junction of the outer end of the posterior border with the lateral border of the palatine process of the maxilla a long internal alveolar process is projected backwards on the inner side of the molar tooth-buds which is entirely independent at this stage of the outer alveolar wall above described.

The os palatinum is of considerable size and consists of a vertical and a horizontal or palatine plate.

The vertical plate is longer from before backwards than in height. It lies lateral to the pars posterior of the nasal capsule and forms a considerable part of the bony infero-internal wall of the orbital cavity. Its junction with the palatine process is overlapped to a considerable extent laterally by the internal alveolar process of the maxilla.

The horizontal or palatine plate is of large size, quadrilateral in form, with its postero-median and postero-lateral angles projected backwards as spurs. A large vacuity is found in the centre of the palatine plate which is of interest, because at this stage is represented a not unusual feature in the adult insectivore, e.g. hedgehog, in which vacuities are found in the adult palate bone. In the adult Miniopterus no such vacuity is met with. The postero-lateral angle of the palatine process at its junction with the vertical plate forms a tuberosity or spur which articulates with the pterygoid bone which lies behind it.

The vomer. This bone is of great length. It commences in front in a single median pointed extremity which lies in the gap between the hinder halves of the Anterior paraseptal cartilages and it lies below the septum nasi. It rapidly increases in size below the septum, especially in breadth, but its upper surface is folded around the lower edge of the septum. When traced further back, it comes to lie medial to the two posterior paraseptal cartilages with which it is in contact and to which it acts as a covering bone. Shortly after coming into relation with the posterior paraseptal cartilages the vomer splits into two limbs each of which diverges from its fellow and goes backwards, following the outward curve of the posterior paraseptal cartilages to their respective cupulae; finally each limb comes to lie under the root of the ala hypochiasmata and is prolonged as a slender process along the side of the pars interorbito-nasalis of the central stem for a short distance.


The history of the mammalian vomer is of great interest and seems to be elucidated by tracing it from the condition seen in the marsupial Dasyurus. In that animal a figure of whose chondro-cranium appears in Broom’s paper, at the 7 mm. stage no vomer is present, nor is it present in a specimen which I have modelled of corresponding age (Fig. A). In this animal there is a long pointed anterior paraseptal cartilage which stretches backwards along the infero-lateral margin of the septum nasi from the lamina transversalis anterior to the posterior wall of the nasal capsule which is in direct fusion with the septum nasi at this stage, but the anterior paraseptal cartilage stops just short of the posterior wall of the capsule. .

At the 9-5 mm. stage (total length) (Fig. B) the anterior paraseptal cartilage has just reached the septal end of the posterior wall of the nasal capsule and to the medial side of its posterior end a small vomer is now present. This vomer is in two symmetrical halves, each of which is on the medial side of the corresponding anterior paraseptal cartilage. It is also projected backwards under the septum nasi for a short distance. No lamina transversalis posterior is present at this stage beyond a slight ridge on the posterior wall of the nasal capsule, but at the 25 mm. stage (Fig. C) the nasal mucosa has burrowed backwards into the thick posterior wall of the nasal capsule and caused it to protrude backwards in the form of a hollow pyramidal cartilaginous structure free of the septum and whose floor is now the lamina transversalis posterior which is triangular in shape with base forwards, and whose inner basal angle, having fused with the posterior end of the anterior paraseptal cartilage, is drawn out by what appears to be interstitial growth of this part of the septum nasi into a long slender posterior paraseptal cartilage, which is entirely free of the septum. The vomer shares in this attenuation if we may so call it so that it still stretches from the medial side of.the posterior end of the anterior paraseptal cartilage past the posterior paraseptal element of the now common paraseptal cartilage and the now formed lamina transversalis anterior as far as the interorbital part of the pars interorbito-nasalis of the central stem. It is interesting to note that when the common paraseptal cartilage fails, as it tends to do in many animals, the failure is at this junctional region between posterior and anterior paraseptal cartilages, and this too is a part which tends to be surrounded by bone derived from tht lateral lamella of the vomer which not only envelopes the paraseptal cartilage but invades it and causes its absorption. In all animals in which the paraseptal cartilages are laid down either as separate structures throughout fetal life or as a common paraseptal cartilage by ultimate fusion the vomer commences to ossify in relation with the medial side of the post extremities of the anterior paraseptal cartilages and it would seem that the formation of a cupula nasi posterior in the manner described, that is by a thrusting back of the posterior nasal wall in the marsupial, through the expansion of the nasal mucous sac (which would seem to be the primitive method), or by separate chondrification as in the cat (Terry), or Bos (Fawcett and Noordenbos) which is presumably Primordial Cranium of Miniopterus schreibersi 343

the later condition, and which leads to the formation of a posterior paraseptal cartilage, provides a scaffold upon which the vomer can extend in a backward direction, and it may explain why the vomer is usually primitively a paired bone which may be regarded then primarily as a covering bone to the medial edge of the anterior paraseptal cartilage of its side, and which extends backwards along the junctional region to the posterior paraseptal cartilage and the lamina transversalis posterior as they develope. Up to this point matters seem fairly simple; the difficulty arises when one enquires why the originally paired yomer should unite to form a single bone at the lower part of the nasal septum, and giving the generally, I think, held impression that the vomer is a covering bone to the septum nasi. Perhaps the question had better be approached by asking another, viz. why should they not fuse? They are bones placed by the side of the middle line; the paraseptal processes of the premaxillae not infrequently fuse, because it is said that the inswinging of the parts of the anterior paraseptal cartilage in relation with them which certainly in many instances occurs and in those animals more particularly in which the paraseptal processes are known to unite, e.g. cat, the nasalia likewise not infrequently fuse in the middle line, so do the frontalia normally, the parietalia tend to do so as age advances, the interparietalia and the supraoccipitalia do the same, so do the pre- and post-sphenoidalia, and possibly the single basi-occipital may have even arisen at some stage in the same way. Should then there be an inherent tendency for paramedian bones to fuse then one may perhaps infer that the vomer shares this tendency: but considering the question from another point of view and that extraneous pressure, such as has been cited as a possible cause of fusion of the paraseptal processes of the incisivum, may not the extraneous pressure of the approximating palatine processes of the maxillae have an infiuence in bringing together the two halves of the vomer?

These speculations merely apply to the condition in the mammal and the phylogenetic story here is purely concerned with the mammal, but it would appear as the outcome of them that the vomer may be regarded as a covering bone primarily to the paraseptal floor of the nasal capsule, and that when the necessity for such a support has gone by the development of palatine processes to the maxillae and palatines has provided a new support to the floor of the nose the vomer has transferred its allegiance to the septum nasi and appeared as a covering bone to that structure: and as such it has become U-shaped by fusion of its originally separate alae. As to its earlier phylogeny much turns on what the vomer as we know it in the mammal really is. If it be homologous with the amphibian vomer, then as is well known the two halves are comparatively widely separated from one another and the maxillae do not meet in the mid-ventral line of the skull, but if the vomer be something else, part for example of the parasphenoid, then there are difficulties. Its apparently constant relation to the anterior paraseptal cartilages and their origin from the lamina transversalis anterior together with the mode of formation of the posterior paraseptal cartilages and the connected laminae transversales posterior together with the intrinsic growth of the nasal septum which stretches out the interval between the laminae transversales anterior and posterior point to the vomer as a structure which has grown backwards rather than forwards, as would appear to be necessary should it be parasphenoidal in origin. It is interesting to note that where the vomer actually encircles the junctional region of the paraseptal cartilage that that appears to be the region most likely to fail to develope as a cartilage, and that the gap is bridged over by what would seem to be the perichondrial representative of this structure prolonged trom anterior to posterior paraseptal cartilages, in which a large part of the vomer developes. I have already pointed out the peculiar mode of origin of the vomer in man, in whom the anterior end has added to it a lateral independent lamella which actually invades the hinder end of the anterior paraseptal cartilage(7).

The pterygoid. This bone consists of the usual parts, namely an upper Jamellar membranous portion and a lower cartilaginous hamulus. The former is inclined over towards the pars trabecularis of the central stem, comes into contact behind with the so-called processus alaris (anterior trabeculo-cochlear commissure), which is here partially ossified, but though coming into contact with this bone lies at a somewhat lower plane than its anterior edge, and its outer edge is overlapped by the cartilaginous forward prolongation of the temporalis as well as by the inner edge of the alisphenoid. It certainly forms a quite considerable element in the bony floor of the cavum cranii.

The hamulus is partly cartilaginous and partly bony ; it is in direct anteroposterior line with the tuberosity of the palate bone and has the usual relations with the tendon of the tensor tympani muscle. The mandibular division of the fifth nerve leaves the foramen ovale lateral to the root of the hamulus. .

The alisphenoid is a large fan-shaped bone which closes below a large part of the spheno-parietal foramen. Its base is of great length and articulates by its whole length with the medial lamella of the lower edge of the parietale. The posterior basal angle passes backwards towards the auditory capsule almost coming into contact with the facial nerve, after it has emerged from under cover of the supra-facial commissure. This angle overlies the forwardly projected tegmen tympani. The anterior basal angle reaches the hinder border of the ala orbitalis. The apical region is directed medialwards and is perforated by the foramen ovale at its middle interval to which the bone envelopes the cartilaginous ala temporalis, i.e. that part which remains unossified. Medial to this the apical region comes into overlapping contact with the lamina of the pterygoid bone and more posteriorly with the processus alaris (ossified) of the post-sphenoid. By its anterior margin the alisphenoid bounds posteriorly the sphenoidal fissure which is here confluent with the incomplete optic foramen (incisura optica). The hinder margin of the alisphenoid forms the anterior boundary of a long fissure in front of the auditory capsule (cochlear part), which is bounded medially by the anterior trabeculoPrimordial Cranium of Miniopterus schreibersi 345 ,

cochlear commissure and transmits the great superficial petrosal nerve. No lamina pterygoidea externa is present.

The sguamosum. This bone is much elongated from before backwards, and low in height. It articulates by the whole length of its upper border with the lower edge of the parietal bone much in the same way as in man. From near the front of the lower margin of the squama a slender zygomatic process passes outwards, then bends suddenly forwards lateral to the processus coronoideus of the mandible. This process then lays itself on the posterior half of the upper border of the zygomaticum with which it articulates. The under aspect of the outwardly directed part of the processus zygomaticus forms a prominent eminentia articularis in which is a laterally elongated mass of cartilage (fig. 18); behind this eminence is the glenoid fossa whose long axis is transverse. It articulates with the processus condyloideus (which is likewise transversely elongated) of the mandible. Behind the glenoid cavity is a very prominent post-glenoid tubercle, behind which is a large foramen, the postglenoid foramen, for the transmission of the lateral jugular vein. From the region of the post-glenoid tubercle the lower margin of the squamosum arches downwards and backwards behind the tympanic bone and comes to an end below and anterior to the root of the processus styloideus which it consequently overlaps. The lower end of this inferior border is separated from the processus styloideus by the facial nerve which is here hooking around the outer side of the processus styloideus. Beyond this region in a backward direction the inferior border of the bone is sharp and straight and to its whole length is attached the sterno-mastoid muscle. For that reason it may be regarded as a mastoid process, but from its continuity with the squamosum is equally entitled to be called the post auditory process of that bone. The posterior edge of the squamosum is almost vertical and overlaps the anterior edge of the lateral semicircular canal.

The tympanicum consists of two parts, viz. the ecto-tympanicum—the tympanic of ordinary terminology—which is a membrane bone, and the endoor meta-tympanicum which is derived from cartilage and forms the tympanic bulla.

The ecto-tympanicum is of much the usual form at such age, is an incomplete ring, open just lateral to the neck of the malleus cartilage and the root of the styloid process. Its upper or anterior limb passes from its commencement behind, forwards along the outer side of the head of the malleus and the root of Meckel’s cartilage, on reaching which it sinks under that cartilage and is separated from it by the goniale(prearticular) ; it then descends to come into medial relation to the processus styloideus, near the ossified part of the latter; it now curves backwards and upwards almost parallel with the processus styloideus and comes to an end just below the commencement of the manubrium mallei and immediately in front of the oblique inner surface of the processus styloideus. In immediate contact with the posterior half of the medial border of the ecto-tympanic is found the ento-tympanicum (meta-tympanicum—Wincza) or tympanic bulla. This is a large curved triangular plate pointed in front, which hides from latero-inferior view the prominentia cochleae and the foramen rotundum, and it supports from below the first pharyngeal pouch which rests upon it, and whose width here is coextensive with the cartilage. Beneath its medial margin (fig. 6) the internal carotid artery, accompanied by branches of the sympathetic, passes upwards along the wall of the cochlear capsule. The most posterior level of the entotympanicum as well as of the accompanying first pharyngeal pouch is reached at the chorda-tympani nerve. The cartilage is a very thin plate and is nowhere ossified at this stage, and it is only connected with the ecto-tympanicum by fibrous tissue. Much has been written in regard to the significance from the morphological point of view, and regarding. the tympanic bulla in general. To my mind from the fact that it resembles very much in its structure the auricular cartilage, the cartilage of the Eustachian tube and that of the younger nasal cartilages, it seems fair to assume that it is really a provision for support of the outer end of the first pharyngeal pouch more especially protecting it from the pressure of the digastric muscle which at this stage is of large size. The Eustachian cartilage does the same for the aditus of the first pharyngeal pouch. In the case of the ento-tympanicum the cartilage remains of the hyaline type which later becomes bone, the requirements of it being merely that of protection. In the case of the Eustachian tube which subserves an additional function, elastic pores are developed to ensure its pliability. Both cartilages may be taken as primitively of equal morphological value, the Eustachian cartilage being a supporting cartilage to the roof and sides of the aditus of the first pharyngeal pouch, the ento-tympanic cartilage being a support to the outer large end of that pouch, and they both chondrify at the same time in the same strand of connective tissue, viz. the connective tissue which surrounds the first pharyngeal pouch.

The petrosum. Much of the auditory capsule has undergone both perichondrial as well as ento-chondral ossification, but as the stain here is not quite as satisfactory as it might be the limits of the ossific centres are not sufficiently easy to describe or model. This is a question which will form the subject of a future communication.

The zygomaticum or malar bone is a small rod-like membrane bone developed in the gap between the zygomatic process of the maxilla and that of the squamosum. It overlaps the former on its outer side and is overlapped by the latter from above. So much overlapping occurs that very little of the bone itself is free.

The post-sphenoid forms the whole of the floor of the pituitary fossa, extending behind to the root of the dorsum sellae and forwards a little in front of the floor of the pituitary fossa. On each side of the fossa a bony arm is projected transversely which is tipped with cartilage, which comes into contact with the cartilage of the ala temporalis and is only imperfectly fused with it. The stage is too old to determine how this region was originally ossified. Primordial Cranium of Miniopterus schreibersi 347

There is no sign of any presphenoidal ossification.

The occipital ossifications.

There are present here, a basioccipital, two exoccipitals, and a supraoccipital.

The basioccipital ossification extends from the front of the foramen magnum and a little distance on each side in front of the hypoglossal canals forwards to about the middle of the cochlear capsule. Towards its anterior end this ossific centre appears to be U-shaped in coronal section, extending further forwards. below and at the sides of the pars chordalis cartilage than above, hence the cartilage appears here to be lodged in the hollow of the U-shaped bone, the hollow being upwards. The notochord has entirely disappeared in the region of this ossific centre.

Each exoccipital centre is here quite independent of the other occipital centres of ossification and commences behind opposite the middle of the lateral wall of the foramen magnum and near the foraminal edge of the cartilage of the exoccipital ; later it is seen to be both ento-chondral and perichondrial, the latter extending on the medial side almost up to the crus commune of the pars canalicularis of the auditory capsule with which the exoccipital cartilage is fused. Still further forwards this peri-chondrial ossification forms the floor of the medial half of the groove for the lateral,sinus, and on the infero-lateral side the cavity of the occipito-atlantal joint is visible, and the ento-chondral centre now is covered below by the articular cartilage of the

‘ occipital condyle which is naturally unossified ; further forwards this cap of articular cartilage becomes separated from the ossified cartilage by unossified cartilage, and the peri-chondrial bone is now forming the outer part of the

_ exoccipito-capsular fissure, and this it continues to do until the level of the

spinal accessory nerve is reached.

Still later, when the lamina alaris becomes evident, peri-chondrial bone spreads under that but not so far as the exoccipito-capsular (supra-alar—Voit) fissure; in fact it reaches to the medial side of insertion of the rectus capitis lateralis muscle. It, on the upper side of the lamina, reaches to the edge of the lateral sinus. The ento-chondral ossification has by now drawn away from the foramen magnum and is concentrated around the hypoglossal canal in its postero-lateral wall, extending somewhat further along the outer side than the inner one. The anterior wall of the hypoglossal canal is quite unossified. The hypoglossal nerve emerges from the canal in two bundles.

The supraoccipital is partly peri-chondrial and partly ento-chondral in ossification and formed thus both around and at the expense of the supraoccipital cartilage. At first, that is at its anterior part, itis mainly peri-chondrial and laid down on the caval side of the supraoccipital cartilage along which it reaches to the level of the hind end of the saccus endolymphaticus and by this time much ento-chondral bone has been formed; later peri-chondrial bone reaches to the outer side of the saccus endolymphaticus, but behind this the cartilage rapidly all disappears, having been completely ossified and it is no longer possible to say whcre peri-chondrial bone ends and ento-chondral bone begins. At this stage the supraoccipital is a single bone forming a bony tectum posterius and completing the foramen magnum posteriorly.

The mandible is a very long bone reaching from the glenoid fossa of the squamosum to the anterior end of the head. Its hind end shows three processes of which the uppermost is the coronoid, the middle the processus condyloideus and the lowest the angular process. Each of these to a large extent consists of cartilage and the cartilage of the angular process is continuous with that of the condyle. In each case the cartilage is elongated in a forward direction and, save at the actual head of the condylar process, is partly ossified. The long axis of the condyle is transverse (fig. 18). Anterior to these three processes the mandible becomes U-shaped, the lateral and medial limbs of the U being the respective alveolar walls anteriorly in relation to the premolar, canine and incisor teeth. Alveolar septa are present so that well-developed toothsockets are present. A double mental foramen perforates the lateral alveolar wall not far from the anterior end of the mandible. At the level of the interval between the first and second premolar tooth-sockets Meckel’s cartilage which, previously lain along the medial side of the mandible, sinks into the bone and becomes surrounded by a bony tube. It again emerges just in front of the canine tooth-socket and soon fuses with its fellow. The medial alveolar wall just above and anterior to the site of emergence of Meckel’s cartilage develops an accessory cartilage (fig. 19) like that which I have described in Microtus amphibius. None of these accessory cartilages is ossified independently and all are quite independent of Meckel’s cartilage and of much later formation.

REFERENCES

(1) Frower and LypEKKEer. Mammals living and extinct. 1891.

(2) Weser. Die Sdugethiere. 1904.

(3) Vorr. Das Primordialeranium des Kaninchens-Anat. Hefte 1. Abt. 116? Heft. (38 Bd., 113).

(4) Turry. ‘The Primordial Cranium of the Cat.” Journal of Morphology, vol. xx1x. No. 2, Sept. 1917.

(5) Fawcett. “The Primordial Cranium of Erinaceus europeus.” Journal of Anatomy, vol. Lu.

(6) Noorpmnzos, W. “Uber die Entwickelung des Chondrocraniums der Saugetiere.”” Petrus Camper. Deel m1. Apl. 3 u. 4.

(7) Fawcert. Journal of Anatomy, vol. xiv. 1910-11. Os Septo-mazillare of Tatusia novemcincta 349

TuE Os SEPTO-MAXILLARE OF T'ATUSIA NOVEMCINCT4A,

This bone, so far as is known, occurs only in Tatusia amongst mammals. Broom (1) first noticed it and Fuchs (2) has given a detailed description of it, and has discussed against Gaupp its morphology. It is not proposed to enter into the question of its morphology here, but merely to describe its position and by alittle alteration in terminology perhaps render its understanding somewhat simpler. Two plates are submitted which are drawings of a model made from the snout of a 60 mm. Tatusia embryo given me by Prof. Wood Jones. In Plate XX a ventral view is given and in Plate XXI a left lateral view.

In Plate XX the septo-maxillare is seen lying immediately ventral to the lamina transversalis anterior, and it consists of two parts, one a body the other an anterior ascending process. The anterior ascending process passes forwards and upwards under cover of the naso-lacrimal duct and lateral to the processus lateralis ventralis of the septum nasi to the supero-medial border of the margino-turbinal. The central part of the body of the septo-maxillare has been cut out in order to show the lamina transversalis anterior lying deep to it. The body of the septo-maxillary bone is concealed from ventral view partly by the palatine plate of the premaxillary (incisivum) bone and to a large extent by the paraseptal process of that bone. On the right side of Plate XX dotted lines show the course taken by the paraseptal process—a structure which ossifies independently of the rest of the premaxillary bone, and is well marked at the 17 mm. stage when the rest of the bone is absent. Evidently the body of the os septo-maxillare is a covering bone to the lamina transversalis anterior and separates the premaxilla from it. In other mammals known to me the premaxilla takes its place in this respect. The relations of the anterior ascending process are not easily understood until one examines the condition of the nasal capsule. An examination of the lateral wall as presented in Plate XXI shows us that a large somewhat triangular fenestra is present in it which has isolated to a great extent the lateral margin of the anterior narial aperture, and the part isolated in this way has become bent upwards towards the nasal cavity to project therein as a prominent spur to which I Have suggested the name margino-turbinal. Some distance above and in front of this marginoturbinal the isolated margin shows the processus alaris superior, whilst below and behind is the processus alaris inferior. The condition recalls that seen in Miniopterus and is-due to the same causes. The two principal causes are first the almost complete isolation of the lateral margin of the anterior narial aperture by the development of a large lateral fenestra (which is not present at an earlier period), and secondly the bending out of the nasal mucosa to find a lateral opening. This outward bend of the nasal mucosa (compare Miniopterus, Pl. XVIII) so affects the margin between the superior and inferior alae processes as to produce a bend towards the nasal cavity which develops into a spur along whose medial side the anterior part of the ascending process of the septo-maxillare lies, but it will be seen that this ascending process is also in relation with another piece of cartilage which in the lateral view through the lateral fenestra appears to project forwards and upwards into the nasal cavity. This cartilage is a spur-like prolongation of the atrio-turbinal which posteriorly is continuous with the maxillo-turbinal. The atrioturbinal is caused in the usual way, viz. by an upbending of the lamina transversalis anterior over the naso-lacrimal duct into the cavity of the nose. At its free upper extremity it divides into two laminae. Between the margino-turbinale and the atrio-turbinale is a deep incisure which is walled in medially by the anterior ascending process of the septomaxillare.

In conclusion it may be said that the septo-maxillary bone is a covering bone by its body to the lamina transversalis anterior and by its anterior ascending process to the atrio- and margino-turbinals. As to why it does not occur in other mammals whose nasal apparatus is so similar I do not know.

A cartilaginous septo-turbinal is present at this stage along the dorsal anterior part of the septum nasi.

Tho expenses incurred by this research were defrayed by a grant from the University Colston Research Society. .

REFERENCES

(1) Broom, R. Journ. of Anat. and Physiol. 1897. (2) Fucus, H. Anat. Anzeiger, xxxvill. Band. 1911. Muse. temp.

t-4-— Os parietale


Ven. cap. lat.





4 Canal. semic. ant.

‘7 Hiatus subase. ant. 1-—_—_—4- Flocculus et fossa subasc, ant,

Crus commune

Cent. ossific.

N. glossoph.

Recess. supraalaris Sinus ven. lat. Promin. semic. post. Recess. exoce. caps. Comm. exoce. caps. Proc. paracondyl.

Os exoccipitale Artic. occ. atlant.

Atlas

Fig. 1. Coronal section through exoccipital, etc. Canal semic. ant. ampulla

Canal semic. lat.

Crista acastica. canal sem. post. Saccus perilymphaticus Centium. ossific.

Promin. semie. lat.

Commiss. chordo cochl.


Muse. temp.


Os squamos.



Vena. cap. lat. Prom. utric. amp. ant. Cristaacusticasemic. ant.


Cristaacustica semic. lat. Prom. semic. lat.

Duct. coch.

Muse. staped.

Cochlea

Muse. digastric.

Fig. 3. Coronal section through auditory capsule at fossa muse. stapedii. Os squamosum

Ven. cap. lat.

For. acustic. sup. et facial. N. facial.

N. vestib. div. sup.

Crista acustic. semic. lat.

Macula sacculi et nervy. Os

Muse. staped. Organ Corti


N. cochl.


Ven. cap. lat. Canal facialis

N. sup. ad macul. saccul.

Macula sacculi

N. facial.

N. inf. ad macul. sace. Stapes

Tend. muse. stapedii Promontorium

Organ Corti

Cart. entotympanic Feenest. coch.

~~ 1st vise. pouch


Fig. 5. Coronal section through auditory capsule at level of foenestive vestibuli et cochleae. Parietale

Ven. cap. lat. Tegmen tymp.

Crus. breve incudis N. facial. Squamosum

Radix crist. parotic. Stapes

Art. staped.

Proc. styloid N. facial.

Cart. entotymp. Muse. digastric.

Art. carotid.

Fig. 6. Coronal section through auditory capsule at level of most fully developed part of entotympanic cartilage which is seen supporting first visceral pouch.

Parietale

Tend. tens. tymp.

N. facial. et chord. tymp.

Os ectotympanic

Cart. entotympanic

M. digastric.


Fig. 7. Coronal section through auditory capsule at level of tendon of insertion of tensor tympani muscle. Duct. gland. lat. nas.




~ Maxillo-turbinale +— Duct. naso-lac.


Lam. med, cart. paras. ant.


Organ. Jacobsoni

Proc. post. cart. duct. naso-pal. °

Lam. lat. cart. paras. ant.

Proc. parasept. os incisivi

Aditus duct. naso-palat.

Cartil. tube of cart. parasept. ant. surrounding duct. organ. Jacobs. Proce. post. cart. duct. naso-palat.

Tect. nasi ant.

Duct. gland. nas. lat. N. nasal.

Maxillo-turb. Duct. naso-lat.

Lam. trans. ant. Lam. med. cart. ant. parasep.


Incisivum

Proc. parasept. os incisiv. Duct. organ. Jacobs.

Lam. lat. cart. paras. ant. Proc. post. cart. duct. naso-pal. Duct. naso-palat.






°

Fig. 10. Coronal section nasal capsule through junction of duct of organ of Jacobson with nasopalatine duct. Tect. nasi

Duct. gland. nasi lat. N. nasal.

Duct. nas. lac.


Duet. nas. palat. Lam. trans. ant.

K mm 2: j

ae oe Lamin. med, cart. paras. ant. ST fA 0



i a6

in Regio. junct.

Shi ia AN Cart. duct. nas. pal. (pars parasept) ) AS Cart. duct. nas. pal.

I SS lag Papilla palatina SH ~ Q atina z i) Outline of course of proc. parasept

of os incisivum

Fig. 11. Coronal section of nasal capsule at level of confluence of lamina transversalis anterior with anterior paraseptive cartilage and cartilage of naso-palatine duct.

Tectum nasi

"i C28 Cy | N. nasal. 5 ci S Sept. nasi

Atrio-turbinale Proc. sup. lamin. trans. ant. Duct. naso-lac.

Lam. trans. ant.

Proc. ant. cart. duct. naso-pal. Cart. papill. palat. Papilla palat.

Fig. 12. Coronal section through nasal capsule at level of cartilage of papilla palatina. 3 Proce. alar. nasi inf.

Prom. lat. atrii nasi


AY Pow Atrio-turb. Sy —— duct. nas. lac. oP r000. lacrim. proc. alar. nasi inf.

ee ‘Lam. trans. ant.

Incisivum

Proc. ant. cart. duct. naso-palat.

Papilla palatina

Fig. 13. Coronal section of nasal capsule at level of apex of processus alaris nasi inferior.

Process. alar. nasi inf.

Prom. lat. atrii nasi

Opening of naso-lac. duct into interior of musc. memb. Radix. proc. lac. proc.alar. inf.

Proce. lac. proc. alar. inf.

Proc. ant. lam. trans. ant.

Proc. ant. cart. duct. nasopalat.

Papilla palatina


Fig. 14. Coronal section of nasal capsule through root of lacrimal process of processus alaris nasi inferior. Margino-turbinale

Proce. alar. nasi inf.

Proc. ant. lam. trans. ant.

Proc. ant. cart. duc. naso-pal.


Tect. nasi

Mucos. nasi

Apert. nar. ant. lat.

Proce. alar. nasi inf.


Proc. ant. lam. trans. ant.

Proce. ant. cart. duct. naso-pal.

Papilla palat.

Fig. 16. Coronal section through antero-lateral part of anterior nasial aperture.

Sule. dorsalis sept. nasi Proc. alar. nasi sup. Ant. lat. nasial aperture

Proc. alar. nasi inf.

- Proc. lat. vent. sept. nasi


Fig. 17. Coronal section nasal capsule, through processus lateralis ventralis. Parietale

Squamosum








. a WSS Cart. emin. artic. SSA = . : : fay SS Temp. mandib. artic. cavit: 5 2 ‘ Cart. condyl. mandib \

Ne

N. auric. temp. Cart. meckel

Goniale

we \)

Access. cart. med. aly. wall of mandible

— Cart. meckel

Fig. 19. Coronal section through anterior part of mandible. oeawaeeesss --+---- Cupula nasi ant. et een eaea nes Apertura nasi ant. aocdeuekios-—---- Proce. alar. nasi sup.


Comm. ali-cupularis wenn - - Margino-turbinale a Proc. alar. nasi inf. =<---* Proc. lat. vent.

SE wn------ Proc. lac. proc. alar. nasi inf. om et ks ot ss oe PY, ¢ Foonest. lat. -...-- Proc. ant. lam. trans. ant.

Fa rene Incis. duct. naso-lac. Proc. sup. lam. trans. ant. '

Proc. ant. cart. duct. naso-pal. Lam. trans. ant.----------- be # Renna cna semen Sept. nasi Cart. papill. pal. ---.------ = a i enn -n=---- Incisivum Incis. post-trans. ------------- '

Lor eee Ph >. Incis-duct. naso-palat.

meres Proc. parasept. os incisivi

~---~ Proc. post. cart. duct. naso-pal. ”” Maxilla

~ Cart. parasept. ant.

Duct. naso-lac. ------- Vomer


Proc. maxill. ant.

Fig. 20. Ventral view of anterior part of solum nasi and anterior end of nasal capsule. Cupula nasi ant.




Corpus os incisivi Mark Hill (talk) — — Lam. trans. ant.

Fig. A. Ventral view solum nasi Dasy -~-" Cart. paras. ant. . 7 urus viverrinus at 7 mm. stage.

Sa eseoa==== — Cupula nasi ant.

eo WEN --------------- Corpus os incisivi

Proc. parasept. os incisivi

baaoses Cart. parasept. ant. Fig. B. Ventral view of solum nasi of Dasyurus viverrinus (Hill embryo). 9-5 mm. ~---- —Vomer stage, total length.

~~ Lamina trans. post.

as Recess. cupul. post.

ee ae Lam. trans. ant.

--- Proc. parasept. os incisivi

Cart. parasept. ant. Fig. C. Ventral view solum nasi Dasyurus viverrinus (WoodJonesembryo). 25mm.

Regio junct. cart. parasept. stage, total length. ant. c. cart. paras. post.

Sept. nasi

Cart. parasept. post.

Lam. trans. post.

Vomer

Ala orbitalis Journal of Anatomy, Vol. LIII, Part IV oe Plate XIII

ee — Cupula nas. ant.







i

Proe. alaris inf.

aaa Sule. dors. nasi

Incisivum

Frontale Maxilla---- a - Duet. nas. lac.



-- Fornix sup. conjunct. ~ Lamina inter-cribrosa

f | Crista galli--~-..

ee : —Prom. frontalis Irend. muse. obl. sup.---- Tiss. orbito-nasalis

Pay —Comm. sphen. eth.

Ala orbitalis

- Incis. opticu. -- Ala hypochiasm.

Oculus --Frontale - Pars. interorb. nas.---Muse. recti ____ mann Pars trabec.

--Cart. meckel. ---Comm. orb. pariet. --Cart. eminen. artic.




Palatinum-----Alisphenoid -.Pterygoid.-- For. ovale trabee. coch.







Ala temporalis Post-sphenoidale _-----ad ---Tegmen. tymp.

Crista trans,

+-- Crista supra-facialis

--For. acust. sup. et lac.

Fiss. basi-coch, ‘For. acust. inf.

Pars chordalis

(Os vasioccip.)~~ -- Fossa subase. ant. int.

--- Crus. commune


Comm. chordo coch For. jugulare --. Proc. condyloideus \-----——————— a no coe .--._. Canal hypogloss.

Exoccipitale

Interparietale ________

Supraoccipitale --.-------- Miniopterus schreibersi. Primordial cranium of 17 mm. (Hill) embryo, from above. Journal of Anatomy, Vol. LIII, Part IV Plate XIV

Cupula nasi ant.

Proce. alar. sup.

. alar. inf,

. Sup. lam. trans. ant.


















rt. meckel, . papille palatin.

. post. cart. duct. nas. pal. . parasep. oss. incis.

Proc. ant. cart. duc. nas. pal.------------ e

Sept. nasi

Cart. parasep. ant. --- . iE ; Maxilla Duct naso-lac.- Me q eee ees ark: tees Eth. turb. I Mus. obliq. inf. __-_.-_____.__ ZZ. : Eth. turb. I as ee eee...


Eth. furb, 1l---..-SSt. = Comm, ‘sph; eth.-.-.42--2-<< Cart. paras. post.

Incis. opticu.

Ala orbitalis,_____- ; ; d i Wf) : ee ~--Cart. ace. proc. coronoid.

--Pars trabec.

> - Cart. acc. proc. condyloid. ---Cart. meckel.

Comm. orb. par...-.-Font. sph. pariet. Ala temp ...---{R ---2----------- mye i Cart. ace. ang. Cart. ace. emin. art.- | Goniale __..Commiss. trabec. coch. ant. s---- Os post-sphenoidale

Cart. ace. condyl.-- --- Tympanicum ---Fiss. vasi-coch.

Proc. styloid..-.4 , - Proc. styloid.


. Zygomaticum Caps. aud..

L Metatympanicum foss.musc. staped

Art. carotic.

- Commiss. chordo---- Basi-occip. _ [coch. aneeeee Canal. hypogloss.

Condyl. occip -- Proc. paracondyl.

<---- Os exoccip.

nee ence nace Supra-occip.

Miniopterus schreibersi, Primordial cranium of 17 mm. (Hill) embryo, from below. \

Journalof Anatomy, Vol. LIII, Part IV “= Plate XV














Supra-0cc. ------ ---- sgt ie > ------------------ =~ Interparietal een Cart. supra occipitale Commiss. supra-oce. caps.

---Commiss. supra occ. caps Fiss. exocc. caps.--+ -Canal. semiare. ant. Prom. semic. post. -Ven. cap. lat.

s-- Tam. |

> Caps. aud, \ \ (Prom. semic. lat.) \

} H Parietale Incus =... j Malleus i Proce. styloid --- a : ; y Proc.] Goniale - a : / alaris et ala temp. : " : 5 : Cart. access. proc, ------3Q@----------.. = : ~~ Post. sphenoida| condyl. Proc. styloid -Pterygoid --Pars trabecularis Cricoid - Ala orbitalis Thyroid

-- Ala hypochias. Thyro-hyal -Comm. sph. eth. - Fiss. orbito-nas.

Thyroid | 7 y -/---------Crista galli hyroid ------ )

Cerato-hyal = / —— Py

Corpus hyale_ .----- :

Soe ee = Maxilla

-—4------Pars intermed. caps. nas.

oo --------Duct. nas. lac.


—Cart. parasep. ant.

weve ee eeeee Mucosa nagalis

. lll CO tst~i‘“‘Ci‘i‘“ RS Pars ant. caps. nas. Mandibula ---* -- Duct. nas. lac. --+------ Proce. ant. cart. duct. nas. pala

fe 4.....------ - Proc. alaris inf.

wm — Incis. ant.

Miniopterus schreibersi, Primordial cranium of 17 mm. (Hill) embryo, from right side. Journal of Anatomy, Vol. LILI, Part IV “SOO Plate XVI


--Proc. med. lam, trans. ant. Proc. alaris inf.

Feenest. lat.

~Ine. lacrim

For. mentale Mark Hill (talk).

Proc. post. cart. duct. nas. palat.


Incisivum

Mandibula ---Canalis infra orb. ---Maxilla

Lacrimale

. \ Caps. nasal. Zygomaticum... Maxilla...

Tendo. muse. obliq. sup.






Ay Olid ccseseeeneses,

Thyroid Oculus

Cricoid --- Ala orbitalis i

Goniale Frontale | Os styloid

Tympanicum Metatympanicum

Squamosum ----- Caps. audit. . Os exoccipitale --~ Hiatus subare. .----- Canalis semic. ant, ------- ’ Z..-Parietale

Cart. supra occ. .--------- Os supra oce, -----------..—..-— . eesccn ---~ Interparietale


Miniopterus schreibersi. Primordial cranium of 17 mm. (Hill) embryo, from left side. Journal of Anatomy, Vol. LIII, PartIV Plate X VII

Parietale









aoeeeee- Alisphenoid

Lam. pariet. ------~"ee"s2

Tegmen. tymp. --~ Prom. utric.amp. -- ant. ant.

Fossa subare. ant.

= —..-- Crista transv.

Interparietale - For. acust. inf.

~---Pars chordulis

Crus conimune -----Fiss. basi-coch.

Comm. chordo-cochl.

For. jugulare

~---- Can. hypogloss.

a----- Basi-oce. Exoccipitale ------->

Miniopterus schreabersi (Hill embryo). Medial aspect of auditory capsule of left side.

For. ovale ---, Alisphenoid -- Ala temporalis

--- Post-sphen. -~-. Comm. trab. cocl

--- Nerv. facialis Journal of Anatomy, Vol. LIII, Part IV

Sulcus dors, sept. nasi -------- Mucosa nasalis Lam. trans. ant. - Duct. naso-lacr. Cart. papill. palat.

Duct. naso-palat.

ns

Miniopterus schreibersi.



goo”

Nasal capsule, viewed from front and below.

“= Plate X VIII

<cos-=- Proc. alaris sup.

—- Cupula nasi ant,

Foeenestra ant. nasi

Proc. alaris inf.

-- Comm. ali-cupularis

- -- Proc. lat. vent.


- ---Incisivum

Proc. ant. duct. nas. pal

Canal. duct. org. Jacc soni Journal of Anatomy, Vol. LIII, Part IV HOST Plate XIX

Palatinum


--- Prom, frontalis

= Sule. ant. lat. et for. epiphaniale







Org. Jacobsoni----- -=--- Cart. parasep. ant.

Proc. post. cart. duc. nas. pal fy ff — ;

Lam. trans. ant...

- Duct. nas. lac.

Proc. ant. cart. duct. nas. pal. --

--- Proc. alaris inf. Fonest. lat. ---- Proc. ant. lam. trans. ant.

-- Proc. alaris sup.

Cupula nasi. ant. pars. medial. ---------7"7777"

Miniopterus schreibersi. Nasal capsule, viewed from right side. Journal of Anatomy, Vol. LIII, Part IV Plates XX and XXI




Cupula nasi ant.

ann Incis. ant.

---Proe. alaris sup. --- Os septo-max.

Foenest. lat.

--Proe. alaris inf.

--- Duct. nas. lac.

--- Proc. lat. vent.

--- Os septo-max.

Nasale ---+4 ---Lam. trans. ant. Incisivum ------ Mucos. nas. --- Proc. paras. incisivi

Maxilla | - Fenest. basal.

- Cart. paras. ant.

Plate XX. Tatusia novemcincta. Nasal capsule, ventral view. ,

--Feenest. lat.


Marg. turb. -- A ‘

Proe. alar. sup.—

-Org. Jacobs. Lam. trans. ant.— . A Mae ee Muce. nas.

Proc. alar. inf.----- =< Paras. ant.

Proc. lat. vent.--- Plate XXI. Tatusia novemcincta. Nasal capsule, left lateral view.



Cite this page: Hill, M.A. (2020, October 27) Embryology Paper - The primordial cranium of miniopterus schreibersi at the 17 millimetre total length stage (1919). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_primordial_cranium_of_miniopterus_schreibersi_at_the_17_millimetre_total_length_stage_(1919)

What Links Here?
© Dr Mark Hill 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G