ON THE VERTEBRATE SKELETON. 303 
opposites at the symphysis menti; and the whole distal portion of the inverted 
arch of the frontal segment is then formed by a continuous bar of bone, modi- 
fied in its form and articulation, and by its dental appendages, in subserviency 
to mastication and other subordinate functions in relation to the human mouth. 
We recognise the centrum of the nasal vertebra in the human skull by the 
position and connections of the bone, 13, notwithstanding it has undergone 
as extreme a divergence from the ordinary cylindrical shape of such elements, 
as its homotype at the opposite extreme of the vertebral column in birds, 
which Cuvier compares to a ‘soc-de-charrue’: it is, in fact, more compressed 
and vertically developed than in the hog (fig. 24, 13); but it is shorter, and 
commonly retains its original individuality. It directly supports the similarly 
modified compressed, and also, coalesced newrapophyses, 14, which termi- 
nating in like manner the series of their vertebral homotypes anteriorly, have 
-undergone the extremest modification. But the arguments which show the 
coalesced prefrontals of the frog, the bird and the mammal to be the special 
homologues of the bones so called in the fish, establish, as a corollary, their 
general homology with those bones, which retain in so much greater a degree, 
and unmistakeably, their neurapophysial characters in that lowest class of 
cold-blooded vertebrates. The nature of the additional complication by 
which those vertebral or archetypal characters are further masked in mam- 
mals, has been already explained in relation to the nasal neurapophyses of 
the hog. The olfactory nerves are transmitted in man, as in that and most 
other inferior mammals, by numerous foramina, 14, ol. The nasal spine, 15, is 
divided, but much-restricted in its growth, and presents a singular contrast 
in that respect to its homotypes, 11, 7, 3, in the succeeding cranial vertebre. 
The development of the neural arch of the nasal vertebra is so modified in 
man, so contracted as well as retracted, that the orbits, instead of being 
pushed apart and directed laterally, have approximated by a kind of reci- 
procal rotation towards the median plane, and have thus gained a directly 
anterior aspect. 
General homology perhaps best explains the import of the continuation 
of the small and seemingly insignificant bones (20, pl) from the roof of the 
mouth “up the back part of the nostrils to the orbit,” where they are 
connected “to the ossa plana and cellule ethmoidee by the ethmoid suture.” 
That the connection is the best possible for the functions of the bone we 
may feel assured, without the sentiment being damped by discerning in it, 
at the same time, the attempt to retain the type, and repeat those constant con= 
nections of the plewrapophysis in question, not only with its centrum (vomer), 
but also with the modified neurapophyses of its proper segment (prefron- 
tals with coalesced olfactory capsules constituting the compound ‘ ethmoid 
bone’ of anthropotomy). The connections of the pleurapophysis, 20, with its 
hzemapophysis, 21, in front, and its diverging appendage, 24, behind, are also 
retained in man ; and in short, all those characters that, depending on the 
essential nature of the palatine bone as the pleurapophysis of its vertebral 
segment, have served to indicate its special homology from man to the fish, 
without doubt or difficulty, to all anatomists (see Table I.). 
The hemapophysis (20) has the usual mammalian expansion, but is unu- 
sually short in man, and coalesces unusually early with the corresponding 
moiety of the hemal spine (22). Besides the normal and constant connec- 
tions with 20 and 22, the hemapophysis, 21, articulates with its fellow, with 
the centrum (13), neurapophysis (14, os planum), and spine (1s), of its 
own vertebra, with the spine of the frontal vertebra (11), with the detached 
portion of the olfactory capsule (19), and with the muco-dermal bone (73). 
It also affords a large surface of attachment to the proximal piece of 
