DISTRIBUTION OF MARINE MAMMALIA. 219 



inhabiting these waters, both belonging to the same genus 

 Monachus. One of these, M. albiventer, inhabits the Medi- 

 terranean 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 Phocidce of the Antarctic Ocean all belong to genera 

 distinct from the Arctic forms and more nearly allied to Mona- 

 chus, the Seal of the Mid -Atlantic. They are of four species, 

 belonging to as many genera: Ogmorhinus, Lobodon, Leptony- 

 chotes, 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 Aus- 

 tralia. Three species of this genus have been established : Hali- 

 core 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 stellei'i, 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 pos- 

 terity a good account of its habits and anatomy. 



