The Book of Household Management by Mrs. Beeton

586. THIS CLASS OF ANIMALS embraces all those that nourish their young

by means of lacteal glands, or teats, and are so constituted as to have a warm or red blood. In it the whale is placed,--an order which, from external habits, has usually been classed with the fishes; but, although this animal exclusively inhabits the water, and is supplied with fins, it nevertheless exhibits a striking alliance to quadrupeds. It has warm blood, and produces its young alive; it nourishes them with milk, and, for that purpose, is furnished with teats. It is also supplied with lungs, and two auricles and two ventricles to the heart; all of which bring it still closer into an alliance with the quadrupedal species of the animal kingdom.