Thus eliminating doubtful forms, or such as naturalists are not unanimous upon, there are, so to say, some ten well-marked species of Otaries, whereof five belong to the so-called Fur, and five to the so-called Hair Seals. In the northern region there are but three peculiar to the West American coasts, &c., whereas seven inhabit the southern region. These latter range over a wide area, from warmer latitudes to the frigid zone. But it is very remarkable that in the whole of the Northern Atlantic none of the Sea Lions are now to be found. It is, however, noteworthy that in the neighbourhood of Antwerp, Professor P. J. Van Beneden has described some few fragmentary remains of a Seal allied to _Otaria_, which he has named _Mesotaria ambigua_. These fossil bones, along with numerous other remains of Pinnipedia and Cetacea, have been dug out of the upper Tertiary strata of Flanders. As regards the precise geographical distribution, this will be referred to in connection with the species themselves. The absolute distinction between Hair and Fur Seals is one rather of degree than of kind, for as we have before hinted, all the family possess, at least in their early condition, evidence of under-fur, sparse or otherwise. But undoubtedly as age advances in some kinds it is very abundant, in others quite the reverse. Hence this character, though so apparent in some cases, is not one thoroughly to be relied on so far as zoological divisions are concerned, though very considerable stress has been laid upon it by some writers. So far as the skin is looked on as a mercantile commodity it unquestionably is a most useful mode of division, but a classification founded thereon must be taken with the accustomed “grain of salt.” [Illustration: Diagram of a Vertical Section of the Skin of the Fur Seal, showing how (_h_) the coarser Hairs penetrate quite through (_s_) the Skin, while (_f_) the Fur has Roots comparatively superficial. (_After Murie._)]