Class 6. Mammalia. Order 9. Pinnipedia. 519 



The Pinnipedia are of considerable size, sometimes even gigantic ; 

 they are marine (a few live in large lakes, e.g., the Caspian Sea), 

 moving with the greatest activity by means of the very flexible 

 posterior portion of the body, whilst the large, baokwardl^'-directed, 

 hind feet function as the caudal fin of a fish. They usually come on 

 shore to rest, to breed, etc. ; they are littoral forms, but can only move 

 slowly upon land. Bared Seals and Walruses are able to walk on all 

 four legs ; the true Seals hop along with great difficulty, arching 

 their backs and pushing themselves forward by means of the tail end; 

 they rest with the ventral surface on the ground ; the fore limbs are 

 not generally used in locomotion. The food consists of Fish and marine 

 Invertebrates (Crustacea, Mollusca). They are usually polygamous; 

 the males are frequently, as in many other polygamous animals, con- 

 siderably larger than the females. They belong principally to cold 

 and temperate regions. 



1. Bared Seals (Otariidse). With small pinnae; long neck; fore limbs 

 large ; they can walk on the feet which are naked below ; thei'e is a large 

 i-idge on all f oiu- feet, lobed on the hind ones ; claws in part rudimentaiy 

 or very small (this holds for all the claws of the fore limb, and for the first 

 and fifth of the hind, whilst that of the middle toe of the hind limb is well 

 developed). The males are always much larger than the females. This group 

 comes nearest to the Camivora, and many of the characteristic pecuharities 

 of the Pinnipedia are not weU marked. Among these are the so-called S e a - 

 Lions or Sea-Bears, whose skins afford the well-known sealskin.* They 

 inhabit the soutliern waters of the South Hemisphere, and the northern regions 

 of the Pacific. 



2. The Walrus {Trichechus lOdobxnus'] rosmarus) is devoid of pinnae, 

 but in most respects is closely allied to the Otariidse, though very pecuhar 

 as regards the dentition. Like the Otariidee this animal can support itself 

 on its fins, which have large borders, the ventral surface of the feet is naked ; 

 the struotui'e of the claw as in the Otariidse. The young animal has -i f , c a, 

 m J, but several of the teeth are small and soon fall out or are never cut, so 

 that the adult usually possesses the following functional teeth : i i, c +, m f. 

 The upper canine is a long tusk, and continues to grow throughout life ; the 

 other teeth are conical at first, but later worn light away. The Wahus feeds 

 on bivalves, worms, etc., which it grubs up with its long tusks from the bottom 

 of the sea. Fairly large ; indigenous to the Arctic regions. 



3. True Seals (Phocidm). Pinnae wanting; neck short; fore hmbs 

 small. The ventral sides of the feet are hairy, and the hmbs are absolutely 

 useless for walking ; border of the feet nan-ow ; claws for the most part well 

 developed. Chiefly in the Arctic regions. 



(a) The genus Phoca with three upper, two lower incisors, and compressed, 

 multitubercular molars. The Common Seal {Ph. vitulina), occasionally 

 the Ring.ed or Marble Seal (Ph. fcetida), and the Greenland Seal 

 (P. greenlandica), occur on the shores of Britain. AUied to Phoca is the Grey 

 Seal (Halichoerus grypus), with conical molars, ocoui-ring on the shores of 

 Northern Europe, including Britain. 



* The sealskin of commerce is deprived of the contoiu? hairs, so that the woolly 

 fur alone remains ; and it has, therefore, a very different appearance from the fresh 

 skin. 



