DEVELOPMENT OF THE SKULL IN THE LACERTILIA. 
633 
The epilryal segment (“columella auris ”) will be described with the sections; the 
stylo-ceratohyals, hypo-hyals, basi- (vel glosso-) liyal, and the divided branchials are 
quite similar to what is seen in the adult (Plate 40, fig. 11 ; and Plate 42, fig. 5). 
Of the transversely vertical sections I have only figured five. The first of these 
(Plate 40, fig. 7) is through the nasal sacs, and shows the curve of the roof in front of 
the inferior turbinals, and behind the nasal glands ; here the septum (s.n.) is deepest, 
and is flanked below by the septo-maxillaries and filiform process of the nasal floor 
( sm.x ., n.fi.); below these parts are the vomers (r.). 
The 2nd section (fig. 8) is through the eyeballs ( e) and ethmoid (p>.e.) ; the end of 
the upper fork, and the broad part of the lower fork, of the orbito-sphenoid (o.s.) are 
severed ; so also are the superorbitals and frontals above, and the palatines (pci.) 
below. 
The 3rd section (Plate 41, fig. 7) is through the pituitary region below, and the 
mid brain (C~) above; the pituitary body ( 'py .), now perfect, is seen resting on the 
basisphenoid ( b.s .), in the Sella turcica; part of the alisphenoid ( al.s .) is seen at the 
top—the upper bar ; and the unossified edge of the basisphenoid, where it joins the 
lower bar of the alisphenoid, below. 
The facets of the basipterygoids ( b.pg .), part of Meckel’s cartilage (ML), the middle 
part of the epipterygoid ( e.pg .), and the ophthalmic branch of the 5th nerve (Y), here 
come into view. 
The 4 th section, Plate 40, fig. 9, is by far the most important; it is the counterpart 
of that described in the half-ripe embryo with the “ columella” (Plate 40, figs. 2, 3, 4), 
and of that in the adult, showing the same element (Plate 45, fig. 6). 
The section is through the mid brain or optic lobes (C~), and cerebellum (C 3 ) ; the 
portio mollis or auditory nerve (VIII) is severed as it enters the vestibule (vb). The 
razor has passed exactly between the fenestra ovalis and fenestra rotunda, along the 
opisthotic bar that divides them. The unossified top of the quadrate (q.), its “otic 
process,” is seen in section carrying the “ supra-stapedial,” which has coalesced with 
it at its edge. 
Where the supra-stapedial runs into the main shaft, or medio-stapedial (' m.st .), there 
the tongue-shaped extra-stapedial (e.st.) runs down the tympanic membrane ( m.ty .); 
the infra-stapedial ( i.st .), behind the stem, is cut through. 
The stapedial base ( st .) is seen fitting into the fenestra of the vestibule ( f.o .); below 
this is the severed “stylohyal” ( s.hy .); the arch of the anterior and the ampulla of 
the horizontal canals ( ci.s.c ., h.s.c .) are seen cut across above ; and the upper bar of the 
alisphenoid (al.s.) is seen at a small distance from the capsule. 
Here the basioccipital (b.o.) is imperfect, on account of the large basal “fontanelle 
the rudimentary cochlea buds out from the part of the capsule that lies above the 
basal plate. 
The 5 th section (Plate 40, fig. 10) is in front of the finished arch, above and through 
the perfect basal plate, and remains of notochord (b.o., nc .); a section of the hyoid 
4 m 2 
