Page:Natural History (1848).djvu/108

98 It has been customary to place the animals of this Order at the conclusion of the series of Mammalia; some eminent zoologists, however, have preferred to fix them between the Carnivora and the Pachydermata, connected with the former through the Seals, and with the latter through the Manatees. This we believe to be their true position.

The Cetacea are exclusively aquatic: unlike the Seals, which occasionally crawl out of the water, and bask in the sun, upon the rocks, the Whales and Porpoises never leave the element in which they are born. Their external form is that of a fish, "in the horizontal elongation of the body, the rounded and smooth surface, the gradual attenuation of the extremities of the trunk, and the development of fins, and especially of the tail as means of progression." We saw in the Seals, the fore paws reduced to mere flippers, by the shortening of the bones of the limb, and by the envelopment of the fingers in the common integument. In the Order before us, the transformation is still more complete; the bones of the arm are still more shortened and flattened; those of the fingers, imbedded in cellular tissue, are so concealed beneath a thick skin, that all external trace of—them disappears, there being even no claws to indicate their number. The limb has become a mere