Genera ofFelidse and Canidse. 107 



It is evident that we have here characters which, if stable, 

 would indicate two or three genera of Hominidae additional to 

 Homo. They are unstable at present ; that is, they are not 

 yet invariably found in any race or species of man, or, in other 

 words, are not so associated with other physical characters as 

 to form a correlated index of them. But experience in palaeon- 

 tology and zoology renders it almost certain that these dental 

 characters will at some future time assume this degree of im- 

 portance by becoming stable. This is already indicated by 

 the fact of their being constant in families at the present time. 



What races will be thus distinguished generically it is 

 not easy to indicate ; but all those with prognathous crania 

 may be safely excluded. It is improbable that Mongolian 

 races will early participate in such a modification, as they 

 have a tendency to prognathism and a generally strong dental 

 development. 



Since the reduction in the number of teeth is intimately 

 connected with orthognathism, it is easy to suppose that it is 

 primarily due to the diminished space allowed by the con- 

 tracted maxillary arcade. This contraction is doubtless due 

 to a deficiency of building-material, consequent on a transfer 

 of force to some other part of the structure during the period 

 of growth. This transfer may be to the superior part of the 

 cranium, which is extended to contain an enlarged brain. As 

 the loss of a tooth from each side has so far been sufficient 

 to accommodate the dentition to the space which it is to 

 occupy, it is not likely that the absence of both I. 2 and 

 M. III. will become established. The reduction in the inferior 

 series is less ; and I do not know of any example of the ab- 

 sence of the external incisors of the lower jaw. The loss of 

 the third inferior molars is, on the other hand, very common. 

 It then may be reasonably maintained that two genera of 

 Hominidas will be at some future day added to Homo — that 

 the latter will include the inferior races of men, and the former 

 the superior — that, although in specific characters there may 

 be a want of greater constancy in the species of the new genera 

 as compared with each other than as compared with the primi- 

 tive and true Homo, they will present cases of what is else- 

 where known in zoology, that the same or nearly the same 

 specific characters may be found in different genera. Under 

 such circumstances the form referred to a new genus becomes 

 at the same time a distinct species. The genera of Hominidaj 

 will then, if the characters become constant, be as follows : — 



I. I; C. 1; Pm. |; M. | Homo. 



I. i ; 0. | ; Pni. f ; M. f Metanthropos. 



1. 1 ; C. \ ; Pm. -|; M. f Epanthropos. 



