Mr. Allen had only the skins in salt and the bones of two North-Pacific species to study, and he does not seem to be aware that the abundance of the under-fur greatly depends on the season and age of the animal when collected; and unfortunately he seems to have had no specimens or skulls of the southern species to enable him to study their characters; yet with these limited materials he has ventured to propose a revision of the species of Otariadæ, and, from the same cause, has suggested the uniting of many incongruous species together. It may be very true that zoologists have erred (myself among the number) in making too many genera and species; but the correction of this error requires as much study and consideration of the entire subject as have been used in their determination; and science is not advanced by hasty alterations founded on a few specimens. The Eared Seals are collected for their oil and skins. Most of the species have very dense under-fur of soft erect hairs between the bases of the longer hairs. These are called “Fur-Seals;” and the skins, when deprived of their long hairs, are very valuable. The dressed furs of the various species and localities are of very different commercial and economic value. The skins of _Neophoca lobata_ (of Australia) and _Phocarctos Hookeri_ (of the Southern Ocean), being nearly destitute of this under-fur, are called _Hair-Seals_ by the sealers. Their skins are of little comparative value, as they are only used like the skins of the Earless Seals (Phocidæ). SYNOPSIS OF THE GENERA. Section I. _Palate produced behind to a line even with the condyles of the jaw. Grinders 6/5·6/5. Under fur sparse._ Sea-lions. Tribe 1. OTARIINA. 1. _Otaria._ Antarctic Seas. East and west coast of South America. Section II. _Palate only extended behind to a line even with the middle part of the zygomatic arch._ Sea-bears. Tribe 2. CALLORHININA. Grinders 6/5·6/5. Skull oblong; face broad, shorter than the orbit; forehead arched. Flap of toes very long. 2. _Callorhinus._ Under-fur abundant. North-west coast of America. Tribe 3. ARCTOCEPHALINA. Grinders 6/5·6/5; face of the skull shelving in front; the fifth and sixth grinders behind the front of the zygomatic arch. Flap of toes moderate. 3. _Phocarctos._ Grinders large, lobed, the six upper with two notches on the hinder edge. Under-fur sparse. South America. 4. _Arctocephalus._ Grinders thick; crown conical. Under-fur abundant. Tribe 4. ZALOPHINA. Grinders 5/5·5/5, large, thick, in a close continuous series; the fifth upper in front of the back edge of the zygomatic arch. 5. _Zalophus._ Grinders large and thick, in a close uniform series. Under-fur sparse. North Pacific. 6. _Neophoca._ Grinders large, thick, all equal, in a continuous uniform series. Under-fur sparse. Flap of toes very short. Australia.