448 TEETH OF SEALS CHAP. 



six, and the additional molar was at the end of the series, thus 

 suggesting a lengthening of jaw coupled with an increase in 

 number of teeth. 



The incisor teeth of the Pinnipedia differ from those of the 

 land Carnivora in that there are nearly always fewer than ^, at 

 least in the adult animal. In possessing lobulated kidneys the 

 Pinnipedia differ from all terrestrial Carnivores except the Otters 

 and Bears a significant fact. 



In the characters of the skeleton the Pinnipedia show many 

 peculiarities. The cranial part of the skull is proportionately 

 to the facial part greater than in terrestrial Carnivora ; there is 

 no lachrymal bone, and the orbit is to some extent defective in 

 ossification. The alisphenoid canal, so important a feature in 

 the Carnivora, may be present or absent. It is present, for 

 example, in Otaria jubata. 1 This genus also has the more 



FIG. 228. Patagonian Sea-Lion. Otaria jubata. x J s . 



primitive small and rugged tympanic bullae, which are inflated 

 and more Cat-like in others. The vertebrae show an interesting 

 Creodont peculiarity in the complex interlocking arrangements of 

 the zygapophyses of the dorsal vertebrae. The ossicula auditus 

 differ from those of their terrestrial allies in their large size and 

 massive growth. In this they have come to be like those of the 

 Whales and Sirenians. 



There is no doubt about their close resemblance o the 



1 Murie, Trans. Zool. Soc. viii. 1874, p. 501. 



