This order contains a class of animals which live in the water, propel
themselves by fins, and have the general form of fishes; yet they are
viviparous, and suckle their young; in these respects forming a
striking contrast to all the other finny inhabitants of the wave. The
principal species are the dolphin, grampus, porpoise, and whale. The
latter is remarkable as being by far the largest creature known to the
animal kingdom.