inhabiting these waters, both belonging to the same genus Monachus. One of these, M. albiventer, inhabits the Mediterranean and the adjoining coasts of the Atlantic, while the other, M. tropicalis, is in these days restricted to some of the smaller and less known islands of the West Indies.
The Phocidæ of the Antarctic Ocean all belong to genera distinct from the Arctic forms and more nearly allied to Monachus, the Seal of the Mid-Atlantic. They are of four species, belonging to as many genera: Ogmorhinus, Lobodon, Leptonychotes, and Ommatophoca. Besides these the Sea-elephant of the whalers, Macrorhinus, is essentially an Antarctic form, though now nearly extinct there, after long persecution by man. But, as already noted, it extends, or has in former days extended, far up the West Coast of America, and is still occasionally found on Santa Barbara Island on the coast of California.
III. Distribution of the Sirenians.
Only two forms of Sirenians are at the present time existing on the earth's surface—the Manatee, Manatus, and Dugong, Halicore,—each representing a distinct family of the Order. The Manatee is an inhabitant of the coasts and estuaries of both sides of the middle Atlantic Ocean, one species, Manatus senegalensis, occurring on the African shores, and another, M. americanus, on the South American coast and in the Antilles. A third species, M. inunguis, so far as we know at present, is found only in fresh water high up the Amazons.
The Dugong, Halicore, is distributed from East Africa, along the shores of the Indian Ocean and its islands, to North Australia. Three species of this genus have been established: Halicore tabernaculi, from the Red Sea; H. dugong, from the Indian Ocean; and H. australis, from Australia; but it is doubtful how far these forms are actually distinguishable.
Besides Manatus and Halicore, a third quite distinct form of Sirenian was formerly an inhabitant of the North Pacific. This was Steller's Sea-cow, Rhytina stelleri, by far the largest animal of the group, which was exterminated by human agency about 1768. Fortunately, recent researches in Behring's Island have been successful in supplying specimens of its skeleton for our principal museums, and Steller, its discoverer, left to posterity a good account of its habits and anatomy.
