40 
MR. W. K. PARKER OK THE STRUCTURE AND 
the rest belonged to T. hybrida, for their skulls were all much wider and more bulbous 
in form, they had much larger cochleae, and were far less ossified in proportion to 
their size. 
In a figure of the lower view of the endocranium, with the auditory capsules 
removed, and the vomers kept in situ, we get things that are very instructive (fig. 9). 
The alse nasi ( al.n .) are seen folding over the external nostrils ( e.n .), which are 
inferior in aspect. The base of the septum, in this fore part, is alate and lobed where 
it gives off the recurrent cartilages (rc.c.); over them the aliseptal walls (al.sjo.) are 
seen. Below, and overlapping the recurrent cartilages, we see the inferior turbinals 
(i.tb.), now, endosteally ossified. The rest of the nasal labyrinth ( al.e ., ll.tb., n.tb., read 
u.tb., m.tb .) shows no bony deposit, externally, although the turbinals are beginning to 
harden within ; these enfoldings are seen on the outer wall. The vomerine series ot 
bones is half as long as the entire skull, the principal vomer (v.) being very large—a 
trough in which the solid intertrabecular beam rests. In front, that bone half overlies 
the anterior paired vomers ( v'.), which are only one-fourth of its length and of its 
width, and are like miniature Razor shells ( Solen ), wide open ; their concavity is above. 
Widening backw r ards, the main vomer send off a short snag, right and left, at its 
hinder third ; its hinder fourth is in two sharp forks, that expose the perpendicular 
ethmoid, and the presphenoid (p.e.,p.s.) in their angle. From the side spur to nearly 
the end of the fork, there is, on each side, a lanceolate scale of bone, one-fourth larger 
than the anterior vomers (v .), these are the posterior paired vomers (v" , the line, by 
mistake, is carried to the left inferior turbinal), bones that help, afterwards, to bind 
the middle vomer to the ossifying ethmoidal masses. 
Just overlying the forks of the vomer we see the forepart of the base of each 
orbitosplienoid ( o.s .) ; the base of each of these bones is nearly equal to the extent of 
the basisphenoid ( b.s .) behind; but there is no presphenoid between them, only the 
hind part of the great median cartilaginous beam. 
These wings are now lesser than those behind them, the alisphenoids (al.s.) ; they 
are only two-thirds their breadth, and reach out, laterally, not quite so far. They are 
free, and emarginate above, the whole of that large cartilaginous band seen in young 
embryos having disappeared. The orbitosphenoids run forwards, as well as outwards, 
binding, obliquely, upon the great turbinal masses (m.tb.)- Besides the upper notch, 
their whole hind margin is sinuous ; and their base is thick, and perforated. The 
anterior margin, below, is carinate up to the outer fourth ; behind this ridge, midway 
outwards, we see the optic foramen (II.). 
The thick alisphenoids (al.s.) have their wide roof perforated, and the fore part of it 
binds upon the thick base of the corresponding orbitosphenoid. The basal part of 
each wing is confluent with, but does not reach back so far as, the basisphenoid (b.s.). 
The anterior margin is concave, and the outer convex; the posterior margin 
projects backwards as an upper and a lower tooth—the latter being a process 
from the thick ribbed part behind the larger foramen ovale (V 3 .), which is, now, in 
