31 



SEALS. 



covered with hair; front claw rudimentary, skin of the soles 

 rigid, warty ; hind-feet rather large, first and fifth toes elongated, 

 with a distinct flap and rudimentary claw; three middle ones 

 shorter, with subacute claws. Tail rudimentary. 



The skull differs from the other Earless Seals in having a di- 

 stinct alisphenoid canal, like the Eared Seals, and it agrees with 

 the Earless ones in having no postorbital process and the mas- 

 toid process strong and salient, its surface continuous with the 

 auditory bullae. Turner. 



In the young " there are in the upper jaw three incisors on each 

 side, the first or inner extremely small, the second a little larger, 

 and the third or outer disproportionately large, being equal to the 

 largest grinders. The canine tooth is displaced, being thrust out- 

 wards beyond the line of the other teeth. There are five grinders 

 with single roots, the fifth very small. In the lower jaw there 

 are five grinders. In the adult the incisors are obliterated, ex- 



Fig. 11. 



Trichechus Rosmarus. Skull, adult. 



cept the lateral pair of the upper jaw. The fifth grinder also 



disappears, and sometimes the fourth." Macgilliv. Nat. Lib. vii. 



I n the very young the cutting teeth f , all, especially the two 



