The two adult skulls are very like the adult skull of _E. nigrescens_, 1013_d_, in the British Museum; but the opening of the internal nostrils is narrower, and their front edge in one is not nearly so angular, and in the other it is rather more arched than in either of the other two skulls, showing that the size of the posterior nasal aperture and the form of its front edge vary in different specimens of this species. The comparison of the young skull with the more adult one shows that the grinders change their position considerably as regards the front edge of the hinder nasal opening. In the young skull of _Euotaria nigrescens_ the hinder end of the tooth-line is very near (not a quarter of an inch from) a line level with the front edge of the internal nasal opening, and the hinder part of the palate in front of the aperture is nearly as broad as the middle of the palate: in the adult skull the hinder end of the tooth-line is a full inch from the front edge of the internal nasal opening, the hinder part of the palate is contracted toward the internal nostril, and the internal nasal opening is lengthened and narrowed; but the real position of the teeth, as compared with the front part of the zygomatic arch, is little altered, though the form of the palate gives them the appearance of being more changed than they really are. These skulls are interesting as showing that _Euotaria nigrescens_, like _Otaria leonina_ and _Morunga elephantina_, is, or was, common to the Falkland Islands and the west coast of South America. The chief character by which the adult skull of _Euotaria nigrescens_ can be distinguished from the adult skull of _Arctocephalus antarcticus_ is, that the hinder or fifth upper grinder and the penultimate or fourth are placed rather in front of the hinder edge of the front part of the zygomatic arch; but the position of the teeth is most distinctive in the skull of the young animal, and loses much of its importance in comparing old skulls together, unless the skulls and teeth are very accurately compared; and even then the distinction is more imaginary than real. I cannot understand Capt. Abbott’s account of this species. He says that “the full-grown Seal is about the size of the common English Seal. The largest skin I have ever seen I do not think measured more than 4 feet in length, perhaps hardly so much. The hair differs in colour, being sometimes grey, and at other times of a brownish tint; that of the young is of a darker brown colour.” All this agrees better with the true _O. falklandica_; but yet he says the skin of his half-grown specimen is now in the British Museum, and that skin is undoubtedly _Euotaria nigrescens_. Has Mr. Abbott confounded the two species in his mind? Or did he forget the animal? for he informed me that there were no Sea-elephants now living on the island. (P. Z. S. 1868, p. 190.)