TEETH. 



907 



genus ; the tooth p. 4 above plays upon that, 

 m. I, below, which has a similar remarkable 

 carnassial modification of form ; they fit, in- 

 deed, almost as Cuvier describes, like the 

 blades of a pair of scissors ; the two teeth 

 in advance of the carnassial in the upper jaw 

 (p. 3, p. 2) in like manner are opposed to 

 the same number of " fausses molaires " (p. 4, 

 p. 3) in the under jaw, and the canine c. 

 above plays upon the canine below ; all seems 

 straightforward and symmetrical, save that 

 the little tubercular, m. 1, above has no op- 

 ponent in the lower jaw. And, perhaps, the 

 close observer might notice that, whilst the 

 upper canine, c., glides behind its homotype be- 

 low, the first upper false molar (p. 2) passes 

 anterior to the crown of the first false molar 

 (p. 3) below ; and that the second false 

 molar and carnassial of the upper jaw are also 

 a little in advance of those teeth in the under 

 jaw when the mouth is shut. 



In passing to the dentition of the Dog 

 (Jig. 580, III. CAMS), formulised by Cuvier as: 



cf l 3 3 - ~ 



fausses molaires 7 7, carnassieres 



44 



11 



, tu- 



2 2 12 



berculeuses \ ; = r-r," it will be ob- 



, & I Tr 



served that here the first upper false molar 

 (p. 1) differs from that in Fe/is, inasmuch as, 

 when the mouth is shut, it preserves the same 

 relative position to its opponent below (p. 1) 

 which the upper canine does to the lower 

 canine, and that the same may be said of the 

 second and the third false molars ; but that 

 with regard to the carnassial above (p, 4) 

 this tooth repeats the same relative position 

 in regard to the fourth false molar below 

 (p. 4), and not to that tooth, m. 1, which 

 Cuvier regarded as the lower homotype of 

 the carnassial ; and, indeed, the more back- 

 ward position of the lower carnassial is so 

 slight that its significance might well be over- 

 looked, more especially as the two succeed- 

 ing tubercular teeth above were opposed to 

 two similar tuberculars below. Cuvier there- 

 fore leaves us to conclude that the tooth 

 which had no homotype or answerable op- 

 ponent above was either the fourth " fausse 

 molaire " below, or else the first. How un- 

 important size and shape are, and how sig- 

 nificant relative position is in the determina- 

 tion of the homologies of teeth as of other 

 parts, may be learnt before quitting the na- 

 tural order of Carnivora ; e. g. by the condi- 

 tion of the dental system in the Bear (Jig. 

 580, II. URSUS). Here the lower tooth, in. 1, 

 instead of presenting the carnassial character, 

 and resembling in form the upper tooth (p. 4), 

 which is the homologue of the upper car- 

 nassial in the dog, has a tubercular crown, and 

 corresponds in size as well as shape with the 

 upper tooth m. 1, to which it is almost wholly 

 opposed, and with the same slight advance of 

 position which we observe in the lower canine 

 as compared with the upper one, and in the four 

 lower premolars (p. 1, p. 2, p. 3, p. 4) as com- 

 pared with their veritable homotypcs above. 

 F. Cuvier divides the molar series of the 



3 _ 3 



genus Ursus into " fausses molaires - r, 



1 1 22 12,, 



carnassieres - - r, tuberculeuses - - = T-T. 



1 1 4, - IT 



The tendency in every thinker to generalise 

 and to recognise Nature's harmonies, has led 

 him here to use the term " carnassiere " in 

 an arbitrary sense, and to apply it to a tootli 

 above (p. 4), which he owns has such a shape 

 and diminished size as would have led him to 

 regard it as merely a false molar, but that the 

 upper carnassial would then have entirely dis- 

 appeared ; and it has also led him to give the 

 name " carnassiere " to a tooth below, m. 1, 

 which he, nevertheless, describes as having a 

 tubercular and not a trenchant crown. In so 

 natural a group as the true Carnivora it was 

 impossible to overlook the homologues of the 

 trenchant carnassials of the lion, even when 

 they had become tubercular in the omnivo- 

 rous bear ; and Cuvier therefore, having de- 

 termined and defined the teeth so called in 

 the feline genus, felt compelled to distinguish 

 them by the same names after they had lost 

 their specific formal character. And if, indeed, 

 he had succeeded in discovering the teeth which 

 were truly answerable or homotypal in the 

 upper and lower jaws, the term " carnassial " 

 might have been retained as an arbitrary one 

 for such teeth, and have been applied to their 

 homologues in Man, the Ruminant, or the 

 Pachyderm, where they are as certainly de- 

 terminable as in those aberrant Carnivores, 

 in which they have equally lost their sectorial 

 shape. But the inconvenience of names in- 

 dicative of such specialties of form will be very 

 obvious when the term " tuberculeuses" comes 

 to be applied to the three hindmost teeth in 

 the Hyaenodon (fig. 577.), which teeth answer 

 to the broad crushing teeth, in. 1, m. 2, and 

 m. 3, in the bear and some other existing Car- 

 nivora. The analogous term " molar," having 

 a less direct or descriptive meaning, is there- 

 fore so much the better as the requisite arbi- 

 trary name of a determinate species of teeth. 



Had Cuvier been guided in his determina- 

 tions of the teeth by their mutual opposition in 

 the closed mouth, and had studied them with 

 this view in the Carnivora, with the dentition 

 most nearly approaching to the typical formula, 

 viz. the bear, he could then have seen that the 

 three small and inconstant lower premolars 

 (p. 1, p. 2, p. 3) were the homotypes of the 

 three small and similarly inconstant premolars 

 above; that the fourth false molar (p. 4) below, 

 which, as he observes, " alone has the normal 

 form," * was truly the homotype of the tooth 

 above (p. 4), which he found himself com- 

 pelled to reject from the class of " fausses 

 molaires," notwithstanding it presented their 

 normal form; that the tubercular tooth, m. I, 

 which he calls " carnassiere " in the lower 

 jaw, was the veritable homotype of his first 

 " molaire tuberculeuse " above (m. 1), and that 

 the tooth in the inferior series which had no 

 answerable one above was his second " tuber- 



* Dents des Mammifcrcs, p. 111. 



