MAMMALIA. 499 
size. We are 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 Delphinide 
are met with in the warm part of the temperate zone. But the Delphinidee 
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 found 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 Rytina to the arctic zone; 
these three genera being the only representatives of the group. 
The Trichechide (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 history 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 Equide. 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, Hyracide, suilines, and 
Equide, 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. 
Ruminants, however, are much more abundant in the old continent in 
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