2 72 Bulleiiii American Museum of Natural History. [Vol. XIII, 



2. As observed by the writer and Wortman in Oxycena ('99, p. 

 144) : " There is reason to believe that the habitual position of the 



foot was digitigrade, but there 

 is no evidence of any retrac- 

 tility of the claws." Begin- 

 ning therefore with a subdigi- 

 tigrade foot, the progression 

 from Oxycena to Patriofelis 

 does not indicate an advance 

 toward secondary plantigrad- 

 ism, as would be the case if 

 these animals were becoming 

 more and more aquatic in 

 habit. On the contrary, the 

 analogy of the feet of the 

 known Oxyaenidge with those 

 of Procyon and Didelphys 

 would indicate that they were 

 used mainly in slow terrestrial 

 or arboreal locomotion, and 



Fig. 4. Patrio/elis fe)OX, typical lumbar ver- 

 tebra, posterior view. 



exceptionally if at all in swimming. 



The Dentition. 



The lack of prehensile power in the feet of Patriofelis is com- 

 pensated for in an extraordinary manner by the increased pre- 

 hensile power in the progressive evolution of the teeth ; this 

 again is analogous to that of the Felidae in its extreme heterodon- 

 tism or specialization, whereas the key-note of dental evolution 

 among the Pinnipedia is a secondary homodontism or reduction of 

 the premolars and molars to a common triconodont pattern. 

 The dental parallelism of the Oxyaenidse with the Felidae is well 

 stated by Wortman ('99, p. 140). 



The progression of both skull and teeth in the Oxyaenidae is 

 towards a raptorial type with increasing temporal and masseter 

 muscles, deep zygomatic arch and large temporal fossa, heavy 

 jaw, deep and broad symphysis, with the biting power concen- 

 trated at three points, namely, the canines, the fourth lower 

 premolar, and the enormous carnassial teeth ; the carnassials 



