MAMMALIA. 499 



size. We care told that Cetacea attained a greater bulk in earlier times 

 than in ours, before whaling expeditions had become so frequent. Cetacea, 

 then, are excluded from the warm regions. Some few of the Delphinidae 

 are met with in the warm part of the temperate zone. But the Delphinidae 

 are the smallest of all Cetacea ; the large, massive species are inhabitants 

 of the frigid zones, so that the native place of Cetacea is the cold waters of 

 both poles. 



The Sirenidia are aquatic, like Cetacea, but less pelagic; they come 

 near the shores, crawl sometimes on the beaches, and ascend the fresh 

 waters a good way above the seas. Some species even are fluviatile. 

 Thus Manati have been foand only in the great rivers of South America 

 and of Africa (also in Cuba, Florida, &c.), which discharge their waters 

 into the Atlantic within the tropics, and, as it seems, in the warmer part of 

 the temperate zone on the American continent. The genus Halicore is 

 proper to the Indian Archipelago, and the genus Eytina to the arctic zone ; 

 these three genera being the only representatives of the group. 



The Trichechidffi (walruses), sub-aquatic or amphibian, as Sirenidia and 

 Cetacea, are inhabitants of the northern seas. 



The Pachydermata, after Cetacea the largest mammals, are inhabitants 

 of warm climates. It is a singular fact to be noticed, that animals which 

 occupy a low position in the class should be -found in the tropical regions, 

 when we know that Cetacea, which are still lower, belong to the northern 

 latitudes, according to the natural laws of the distribution of the animal 

 kingdom, whose lower groups are always found in the coldest climate. But 

 pachyderms cannot be said to belong to our epoch, and therefore cannot be 

 subjected to the same law. We must therefore find in the past historj^ of 

 the class the reasons of its actual distribution. Let us state now that a 

 single pachyderm is found originating from Europe, the hog, and among 

 pachyderms a small species. In central Asia, six species, one hog also 

 and five horses; in southern Asia, four species, a suiline, an elephant, a 

 rhinoceros, and a horse; and in the Asiatic Archipelago, nine species, 

 an elephant, two rhinoceroses, and six hogs. In the north of Africa, 

 three species only occur, a hippopotamus, a daman, and a hog; in 

 central and southern Africa together, seventeen species, an elephant, a 

 hippopotamus, four rhinoceroses, three damans, four hogs, a tapir, and 

 three Equidse. In the new world and south, four species are found, two 

 peccaries and two tapirs, one species advancing in the warmer parts of 

 North America. In southern America, three species, two peccaries and 

 one tapir only. 



The elephants, rhinoceroses, hippopotamuses, Hyracidte, suilines, and 

 Equidas, are exclusively peculiar in the present day to the ancient hemi- 

 sphere, and, therefore, the majority of the pachyderms. The peccaries are 

 exclusively inhabitants of the New World, and this is nearly the case for 

 the tapirs, a species only being found in southern Africa. 



The ruminants are distributed all over the world, and seem created for 

 the temperate region, although some species extend north and south. 

 Euminants, however, are much more abundant in the old continent in 



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