in six genera; but more generic names have been proposed. At the other extreme stands Dr. Mivart, who speaks of only one genus, Otaria; of this genus the number of species is by no means agreed upon. There can, however, be no doubt of the distinctness of the Northern Fur Seal, O. ursina (the "Seal" of commerce and the cause of international complications), of the Patagonian Maned Sea-Lion, O. jubata,[1] of O. pusilla of the Cape, of the Californian O. gillespiei, of O. hookeri from the Auckland Islands, and of four or five others. The range of the genus is wide, but is mainly Antarctic. It is usual to speak of "Hair Seals" and "Fur Seals," the latter being the species which produce the "sealskin" of commerce. The difference is that in the Fur Seals there is a dense, soft under-fur, which is wanting in the other group. It is, however, impossible to make this character the basis of a generic subdivision. There is a Fur Seal, O. nigrescens, in South America as well as the more widely-known northern form.
Fam. 2. Trichechidae.—This family contains but one genus, Trichechus, the Walrus or Morse, or Odobaenus, as the more correct term seems to be. It is a tiresome result of accurate conformity with the rules of priority in nomenclature that the name Trichechus should be applied to the Manatee. There is but one species of Walrus, though it has been attempted to show that the Pacific and Eastern forms are different. The animal is Arctic and circumpolar. The Walrus is characterised by the enormous canines of its upper jaw, which form the well-known tusks and reach a length of 30 inches. The animal can progress on land like the Sea-Lions; but, as in the Seals, there are no external ears, though there is a slight protuberance above the meatus auditorius. The strong bristles upon the upper lip are as thick as crow quills. The pectoral limb has nails, but these are small, as in the Sea-Lions. The under surface of the manus has a warty pad, which cannot but assist[2] in maintaining a foothold upon slippery ice. The hind-limbs have longer nails, which are still diminutive and subequal in size. There is no free tail. The liver of this animal is much furrowed, but not so much so as in Otaria, though more so than in Phoca. The kidneys are of course lobulate, as in the other aquatic Carnivores. The milk dental formula appears to be I 3/3 C 1/1 Pm + M 5/4. In the adult the formula[3] is I 1/0 C 1/1 M 3/3.
