It is in the shape of the head that the sperm whale differs, in the most remarkable degree, from the right whale—the shape of whose head more resembles that of a porpoise—and in it the spout-hole is situated much farther back, rendering it seldom or never necessary for the nose to be elevated above the surface of the water. The eyes, in both the sperm and right whale, are exceedingly small in comparison with their bulk; still, they are tolerably quick-sighted. We are not aware that the sperm whale possesses, in any respect, any superiority. We again observe, in the formation of the mouth, a very remarkable difference in the two animals; for, in place of the enormous plates of whalebone which are found attached to the upper jaw of the right whale, we only find depressions for the reception of the teeth of the lower jaw, which plainly point out that the food of the two animals must be very different. [Illustration: RIGHT WHALE BONE.] There are several prominences or humps on the back of the sperm whale, which constitutes another difference in their external aspect. These prominences are not altogether peculiar to the sperm whale, as there is a species of fish, called by whalemen “humpbacks,” which possesses a prominence on the back very similar to that of the sperm whale. The skin of the sperm whale is smooth, but occasionally, in old whales, wrinkled. The color of the skin, over the greatest part of the body, is very dark. In different whales there is considerable variety of shade; some are even piebald. “Old bulls,” as full-grown males are called by whalemen, have generally a portion of gray on the nose above the fore-part of the upper jaw, and they are then said to be “gray headed.” In young whales the “black skin,” as it is called, is about three eighths of an inch thick, but in old ones it is not more than one eighth. Immediately beneath the black skin is the blubber, or fat, which is contained in a cellular membrane, and which is much strengthened by numerous fibres. The average thickness of the fat on the breast of a large whale, when in good condition, is about eighteen inches. The “hump” is generally the thickest part of the blubber, being sometimes from twenty-two to twenty-six inches in thickness; and, in most other parts of the body, it measures from nine to fourteen inches. The head is not, however, supplied with this covering, or blubber, having only the black skin, which lies close to a layer of very dense cellular tissue, under which is seen a considerable thickness of numerous small tendons, intermixed with muscular fibres. This thick covering of blubber, or fat, is called the “blanket;” it is of a yellowish color, and, when melted down, furnishes the sperm oil. It also serves two excellent purposes to the whale: rendering it buoyant, and furnishing it with a warm protection from the coldness of the surrounding element—in this last respect, answering well to the name bestowed upon it by whalemen.