DEVELOPMENT OF THE SKULL IN THE MAMMALIA. 211 
were separate, here they communicate, below, under the vomer; here the middle of 
the palatine skin is keeled again; it was flat in the last two sections 
Section 12.—In this section (Plate 30, fig. 12) the fore part of the olfactory lobes 
(C™.) are cut across as they lie in the large fossee upon the ossifying cribriform plate 
(cr.p.). Part of the roof-cartilage is seen right and left, and from the walls and floor 
copious turbinal growths (w.tb., m.tb.) ave seen. Here, the frontals (/-) are perfect and 
roof the whole over, whilst below, the palatines and vomer (pa., v.) are seen in 
section, protecting the small, square naso-palatine passage (i.p.c.). 
Here the perpendicular ethmoid (p.e.) is spear-shaped above, and clubbed below ; it 
is very thin for the most part. The jugal process of the maxillary (j.) is seen, the 
mandibles and teeth (d.), with tongue, below. 
Section 13,—This (Plate 30, fig. 12) is from a little further back behind the general 
roof, and where the frontals (f:) do not meet in the middle; one description may serve 
for both of these sections. 
Section 14.—This (Plate 30, fig. 13) is through the hemispheres (C!.), the great 
fontanelle, at the back part of the frontals (/:), and the large orbito-sphenoidal wings 
(o.s.); the basal part, here, is behind the middle ethmoid, and is the front of the 
presphenoid. The cribriform plate still comes into section in its hindmost part ; this 
is where the skull-walls (0.s.) are united to the olfactory capsules. This is behind the 
vomer, and the low bulbous section of the basis cranii (p.s.) lies over a triangular 
section of the nasopalatine passage. The bony alisphenoid («/.s.),* is seen outside the 
nasal wall. 
The palatines and pterygoids overlap at this part, and here the frontal (/) gets well 
under the skull in the imperfect orbit. 
The articular and angular processes of the lower jaw (cd.p.) and MeckEv’s cartilage 
(mk.) are cut across, close in front of the ear-drum. 
Here the nasal cavities are small, oblique, and reniform in section, in this, their retral 
subcranial part. The wall, although well coiled round the cavity, does not completely 
wall it in; the median cartilage (p.s.) is some distance from the walls. 
Section 15.—In this partial section (Plate 30, fig. 14), the basioccipital (.0.) 1s cut 
across in its front part; on the side, at some distance, the cochlear and part of the 
vestibular region of the auditory capsule are cut through; the wall, very thin, is 
ossified. The prootic plate (pr.o’.) is seen in section, with the hind part of the 
squamosal (sq.) outside and below it. The ossifying opisthotic region, outside and 
below the vestibule, shows the facial nerve (VII.) in its whole course—infra-cranial, 
auditory, and extra-cranial—escaping close behind the sigmoid hyoid arch (e.hy., e.hy); 
the stapes (st.) is partly seen, and also the folds of the concha auris (me., 7.@.e.). 
Section 15.—In this still more limited section (Plate 30, fig. 17) the ossifying auditory 
capsule is cut through across the fenestra ovalis (/%.0.) and the bar between it and the 
fenestra rotunda. The well-formed stapes (sf.) is seen im situ; its head and neck and 
* The line in the figure is too short. 
2E 2 
