OTARIIDA1 593 



They always come on shore, however, for the purpose of bringing 

 forth their young. They are generally marine, but they occasion- 

 ally ascend large rivers, and some inhabit inland seas and lakes, as 

 the Caspian and Baikal. Though not numerous in species, they 

 are widely distributed over the world, but occur most abundantly 

 on the coasts of lands situated in cold and temperate zones. The 

 suborder is divisible into three well-marked families : the Otariida, 

 Fur-Seals or Sea-Bears, which form a transition from the Fissiped 

 Carnivora to the Seals ; the Trichechida>, containing the Walrus ; and 

 the Pliocidce or typical Seals. 



The resemblances between the skull and other parts of the 

 body of the Fur-Seals and the Ursoid true Carnivora is suggestive 

 of some genetic relationship between the two groups, and Pro- 

 fessor Mivart 1 expresses the opinion that the one group is the direct 

 descendant of the other. The same writer goes on to suggest that 

 if the Eared-Seals have been derived from Bear-like Carnivores this 

 need not necessarily hold good with the true Seals, which may have 

 had another, and possibly Lutrine, origin. The presence of an 

 alisphenoid canal in Ursus and the Otariidce, and its absence in Lutra 

 and the Phocidce, together with other osteological features, are cited 

 in support of this view ; but although these resemblances and 

 differences are certainly remarkable, yet much more evidence is 

 required before the hypothesis can be accepted as even a probable 

 one. It must, moreover, be borne in mind that the true Bears are 

 a very modern group ; and there is a possibility that the Pinnipeds 

 may prove to have been independently derived from the extinct 

 Carnivora noticed below under the name of Creodonta. 



Family OTARIID.E. 



When on land the hind feet are turned forwards under the body, 

 and aid in supporting and moving the trunk as in ordinary mammals. 

 A small external ear. Testes suspended in a distinct external 

 scrotum. Skull with postorbital processes, and an alisphenoid canal. 

 Angle of mandible inflected. Palms and soles of feet naked. 



Otaria.* Dentition: i f, c \, p ^, m 1 -y-- ; total 34 or 36. 

 First and second upper incisors small, with the summits of the 

 crowns divided by a deep transverse groove into an anterior 

 and a posterior cusp of nearly equal height ; the third large and 

 canine-like. Canines large, conical, pointed, recurved. Molars and 

 premolars usually 4, of which the second, third, and fourth are 

 preceded by milk-teeth shed a few days after birth; sometimes (as 

 in Fig. 271) a sixth upper molar (occasionally developed on one 



1 Proc. Zool. Soc. 1885, p. 497. 



2 Peron, Voyage aux Tcrres Australes, vol. ii. p. 37 note (1816). 

 38 



