The furs of the different species of Fur-Seals are exceedingly different in external appearance, especially in the younger specimens, or when the fur is in its most perfect condition. In most species the hairs are much longer than the under-fur; they are flat and more or less rigid and crisp. In others the hairs are short, much softer, scarcely longer than the soft woolly under-fur; in these species the fur is very dense, standing nearly erect from the skin, forming a very soft elastic coat, as in _O. falklandicus_ and _O. Stelleri_. The hair of _O. nigrescens_ is considerably longer than that of _O. cinerea_, but not so harsh, the fur of the half-grown _O. nigrescens_ being longer, sparse, flat, rather curled at the end, giving a crispness to the feel; while the hairs of the very young specimens are abundant, nearly of equal length, forming an even coat that is soft and smooth to the touch. The length, abundance, and, indeed, the presence or absence of the under-fur greatly depend on the season at which the specimen is obtained or observed. It is true that the sealers call some seals hair- and others fur-seals; but that is only because what they call hair-seals never had more than a very small quantity of under-fur in the fur-season; but, on the other hand, many fur-seals at some seasons have only a small quantity of the under-fur which is so long and abundant at other periods. Difficult as it is for the zoologist to distinguish the species by their external appearance, the skins of the different species of Fur-Seals are easily distinguished by the dealers, even when they are wet, showing that the practical fellmonger is in advance of the scientific man in such particulars, as the dealers in whalebone were in regard to the distinction of the species of the Whale by their baleen (see Zool. Erebus & Terror). The longer hairs of the Fur-Seals are very slender and pale-coloured at the basal half of their length, and thicker and darker at the upper half, and often have a white tip. The basal half is subcylindrical, the upper half is flat, tapering at each end. The absolute length of the under-fur differs in the various species. Judging from the old and young specimens of _A. nigrescens_, the hairs seem to be longer, both absolutely and relatively to the under-fur, in the young than in the adult animals. The hairs of the Hair-Seals are shorter, flat, channelled above, and gradually tapering from the base to the tip, merely contracted at the insertion into the skin. The breadth of the hairs seems to vary in the different species; and in the younger specimens there are to be observed some soft hairs like the under-fur of the Fur-Seals. The _Fur-Seals_ are _Callorhinus ursinus_, _Arctocephalus antarcticus_, _A. nigrescens_, _A. cinereus_, _A. Forsteri_, _A. falklandicus_, _Eumetopias Stelleri_, _Arctophoca Philippii_. The _Hair-Seals_ are _Otaria jubata_, _Phocarctos Hookeri_, _Arctocephalus nivosus_, _Zalophus Gilliespii_, _Neophoca lobatus_.