tOOTH-GENESIS IN THE CANlDa!. 469 



individual skulls,in which the tooth-cusps were more complete («. e. 

 least worn), for special illustration, but the general conclusion 

 was in entire accordance with the view just stated. 



The outcome of these considerations, with regard to Otocyon, 

 is — that it is primitive in respect to the number, but specialized 

 in respect to the multituberculate condition of its teeth. 



, These conclusions are apparently in direct contradiction to those 

 arising out of the study of the genus Cyon. The members of 

 this genus are distinguished from the true Dogs chiefly by the 

 loss of the last lower molar. I have already drawn attention to 

 the fact of the great simplicity of ^ of Cyon rutilans, a tootli 

 more primitive even, according to my views, than dpm.* of the 

 Dog. 



I am not in a position to do more than suggest, as a possible 

 explanation, that the genus Cyon became separated oflF from the 

 true Dogs at an early period, and that its teeth, while retaining 

 the simplicity of their crowns, have undergone numerical reduction. 

 These animals also differ from the ordinary Wolves, -Jackals, and 

 great majority of domestic Dogs, according to Huxley (7), in the 

 breadth, of the jaws and the convexity of the facial line. I would 

 emphasize the great resemblance which exists, both in the number 

 and pattern of the teeth, between the members of this genus and 



Viverrinoe, as tending to the suggestion that they have all descended 

 from a common stock, early separated from the true Canidae. 



Ewibryological Evidence as to the order of Cusp -development. 



The value of evidence of this nature is based unon the assump- 

 tion that Ontogeny recapitulates Phylogeny. Of course this 

 assumption may be doubted, but it is interesting to note that 

 Osborn, a great upholder of the tritubercular view, believes in 

 it strongly, as may be gathered from the following. In an address 

 " On the History of the Cusps of the Human Molar Teeth," 

 delivered before the New York Institute of Stomatology in 

 April 1895 (15), occur the following words : — " We should expect, 

 in the embryonic jaw, that the calcification of the tooth-germ 

 would be very significant, because we know that the embryonic 

 structures in their development follow the order of addition or 

 evolution." Having made this definite statement, in the next 

 sentence he makes a partial retraction by saying, " The order of 



LINN. JOUBN. — ZOOLOGY, VOL. XXV. 38 



