The whalebone whales are either _smooth-backs_ (Balænæ), or _fin-backs_ (Balænopteræ), having a vertical fin rising from the lower part of the back. To the former belongs the mighty Greenland Whale (_Balæna mysticetus_), the most bulky of living animals, and of all cetaceans the most useful and important to man. Its greatest length, according to Scoresby, is from sixty to seventy feet, and round the thickest part of its body it measures from thirty to forty feet, but the incessant persecutions to which it is subjected scarcely ever allow it to attain its full growth. The whale being somewhat lighter than the medium in which it swims, its weight may be ascertained with tolerable accuracy; and Scoresby tells us that a stout animal of sixty feet weighs about seventy tons, allowing thirty to the blubber, eight or ten to the bones, and thirty or thirty-two to the carcase. The lightness of the whale, which enables it to keep its _crown_, in which the blow-hole is situated, and a considerable extent of back above the water, without any effort or motion, is not only owing to its prodigious case of fat, but also to the lightness of its bones, most of which are very porous and contain large quantities of fine oil; an admirable provision of nature for the wants of a creature destined to breathe the atmospheric air, and to skim its food from the surface of the waters. The unsightly animal shows disproportion in all its organs. While the tail fin measures twenty-four feet across, the pectoral fins or paddles are no more than six feet long. The monstrous head forms about the third of the whole body, and is furnished with an equally monstrous mouth, which on opening exhibits a cavity about the size of an ordinary ship's cabin. The leviathans of the dry land, the elephant, the rhinoceros, and the hippopotamus, are provided with tusks and teeth corresponding to their size--huge weapons fit for eradicating trees or crushing the bone-harnessed crocodile; but the masticatory implements of the giant of the seas are scarcely capable of dividing the smallest food. Instead of teeth, its enormous upper jaw is beset with about 500 laminæ of whalebone, ranged side by side, two-thirds of an inch apart, the thickness of blade included, and resembling a frame of saws in a saw-mill. Their interior edges are covered with fringes of hair; externally they are curved and flattened down, so as to present a smooth surface to the lips. The largest laminæ, situated on both sides of the jaw, attain a length of fifteen feet, and measure from twelve to fifteen inches at their base; in front and towards the back of the mouth they are much shorter. [Illustration: Skull of Whale, with the Baleen.]