ON THE VERTEBRATE SKELETON. 319 



Cuvier affirms, however, in support of his argument, that, although the 

 orbitosphenoids are never separated from the frontals, as the alisphenoids are 

 from the parietals, in the mammalia, they are almost always separated from 

 the frontals in the other classes, so that the vertebral ring is again inter- 

 rupted *. But, were even the frontals commonly uplifted above the orbito- 

 sphenoids in birds, reptiles and fishes, which does not accord with my ex- 

 perience, the objection, on that score, to regarding them as ' neural spines,' 

 would as little apply, as it does to the universally recognised general homology 

 of the separated and uplifted neural arch of the first vertebra of the trunk 

 of the Ephippus and some other fishes. 



Cuvier finally regards the connection of the frontals with the prefrontals, 

 which he calls ' ethmoid ' in mammals, ' l'enchassement de l'ethmoide,' as a 

 function quite remote from any of a vertebral character, " relative a toute 

 autre chose." This objection only shows the necessity of a right apprecia- 

 tion of special homologies, in order to form a true judgement respecting 

 general homology ; and, with respect to the ' ethmo'ide,' I must refer to the 

 section on the prefrontals in the chapter on ' Special Homology (p. 214). If 

 the arguments there adduced be held to prove the crista galli and cribriform 

 plate in the human skull to be the homologues of portions of the coalesced 

 prefrontals and olfactory capsules, we may next remark that these portions 

 are not merely wedged between the orbital plates of the frontal, but axticu- 

 late behind by a persistent suture with the orbitosphenoids. As neurapo- 

 physes, the coalesced prefrontals of the terminal vertebra of the skull thus 

 articulate with their next succeeding homotypes ; and, by virtue of the ex- 

 cessive development of the spine of the frontal vertebra, as well as from their 

 being contracted and drawn backward in the human skull, they articulate 

 with such spine (the frontal) as well as with that of their own proper seg- 

 ment (the nasals). But, in the crocodile (fig. 9), we have seen a similar 

 relation manifested not only by the more normal neurapophyses (14) of the 

 nasal vertebra, but likewise by those (10) of the frontal, those (6) of the 

 parietal, and those (2) of the occipital vertebra. 



All the objections raised by Cuvier to the general homology of the cranial 

 bones as modified vertebral elements, equally apply to elements of vertebras 

 in the trunk, which Cuvier himself has admitted to be vertebrae, notwith- 

 standing such modifications. The repetition of the perforated character of 

 the human alisphenoid and orbitosphenoid in the neurapophyses of the trunk- 

 vertebrae of many inferior animals, requires only a passing notice. The 

 flattening, expansion and sutural union of the human supraoccipital, parietal 

 and frontal bones, are matched by the neural spines in the carapace of the 

 tortoise. If the basioccipital, basisphenoid and presphenoid are broad and flat, 

 instead of cylindrical, so likewise are the bodies of the sacral vertebrae in the 

 broad-bodied megatherioids and in many birds. If the basioccipital and 

 basisphenoid are lengthened out and firmly united together by deeply in- 

 dented sutural surfaces in most fishes, so likewise are the bodies of the four 

 anterior vertebras of the trunk in the pipe-fish (Fistularici). If the basi- 

 sphenoid and presphenoid be developed each from two ossific centres, as in 

 man, so likewise may the body of the human atlas be ossified; and even should 

 the moieties of that centrum not coalesce at the median plane, they would 



* " Ce que j'ai dit des parietaux s'applique aux frontaux, considered comme complements du 

 spheno'ide anterieur ; leur fonction est relative a. toute autre chose, a la protection des lobes 

 anterieurs du cerveau et a. l'enchassement de l'ethmoide ; et quoique le spheno'ide anterieur 

 n'en soit jamais separe dans les mammiferes comme le posterieur Test souvent des parietaux, 

 il Test presque toujours dans les autres classes, en sorte qu'alors l'anneau vertebral serait 

 aussi interrompu." — I.e. p. 714. 



