The skull of Capt. Abbott’s animal is evidently not the same as the skull of a young Eared Seal described and figured by Dr. Burmeister as the skull of _Arctocephalus falklandicus_ from the mouth of the Rio de la Plata, in the Ann. & Mag. Nat. Hist. ser. 3, vol. xviii. p. 99, t. 9, which, from the appearance of the grinders, I suspect is the young skull of _Phocarctos Hookeri_, the Hair-Seal of the Falkland Islands. There is a considerable difference in the proportions of the skull sent by Capt. Abbott from those of the one figured by Dr. Burmeister. In Capt. Abbott’s specimen the brain-case, from the back edge of the orbit to the occiput, is as long as the length of the face, from the same edge of the orbit to the end of the nose. In Dr. Burmeister’s figure, the face from the same point is much longer than the brain-case. *** _Fourth, fifth, and sixth upper grinders with two diverging roots; the fifth upper grinder entirely behind the hinder edge of the zygomatic arch. The palate narrow._ Gypsophoca. (Australia.) 3. Arctocephalus cinereus. _Australian Fur-Seal._ Otaria (Arctocephalus) cinerea, _Peters_, _Monatsb._ 1866, pp. 272 & 671. Arctocephalus nigrescens, _b_ & _c_, _Gerrard_, _Cat. Bones B.M._ p. 147. Black Seal, Otaria, _Cat. Sidney Museum_, ii. p. 36. Arctocephalus cinereus, _Gray_, _Cat. Seals and Whales_, p. 56; _Ann. & Mag. N. H._ 1866, xviii. p. 236; _Allen_, _Bull. Mus. Comp. Zool._ ii. p. 45. Inhab. Australia (_John Macgillivray_). Black, greyer beneath; under-fur abundant, reddish brown. There are the stuffed skin, with its skull, and the bones of the face of another young specimen of this Seal in the British Museum, collected in the Australasian Sea by Mr. John Macgillivray. According to the observations of Dr. Peters, founded on the examination of the typical skulls, _Otaria ursina_ of Nilsson and _Otaria Lemarii_ of J. Müller (Arch. f. Naturg. 1841, p. 334) include the _Arctocephalus antarcticus_ from South Africa and _A. cinereus_ of Australia. _Otaria Stelleri_ of Schlegel (Fauna Japonica, t. 22. f. 55) includes both the Australian Eared Seals, viz. _Arctocephalus cinereus_ and _Neophoca lobata_; and it is quite distinct from the _Otaria Stelleri_ of Lesson and T. Müller, which is a combination of the Sea-bear and Sea-lion of Steller (that is to say, _Eumetopias Stelleri_ and _Callorhinus ursinus_). The males of these animals are described as twice as long and broad (that is, four times as large) as the females. This may explain the difference in size of the skulls from the same localities. The fur changes its colour as the animal grows, the young being generally black; and the adult males and females also differ considerably in the colour of the fur. The skulls of the following species are not known:— 4. Arctocephalus Forsteri. Grinders 6/5·6/5, conical. Arctocephalus Fosteri, _Fischer_; _Gray_, _Ann. & Mag. Nat. Hist._ 1868, i. p. 219.