The sperm is by far the largest member of the toothed whale family and has from eighteen to twenty-five massive teeth on each side of the lower jaw; these fit into sockets in the upper jaw and assist in holding the whale’s food. Upper teeth are also present but are in a rudimentary condition and, except in rare cases, do not protrude into the sockets; undoubtedly in ancient times the upper teeth were as well developed as the lower but since they have not been needed they have gradually atrophied and almost disappeared. Like the teeth of other animals, those of the sperm whale are hollow in the basal half of their length for the reception of nerves; in young whales this nerve cavity is wide and deep but it almost closes with increasing age. [Illustration: “The sperm ... has from eighteen to twenty-five massive teeth on each side of the lower jaw; these fit into sockets in the upper jaw and assist in holding the whale’s food.” ] Quite frequently the lower jaw of an immature animal will be injured and as the whale grows its jaw becomes twisted like an enormous corkscrew. The widespreading posterior part of the jaw is called the “panbone” and from it the sailors make walking sticks, pie-markers, hairpins, and carvings which are often beautifully executed. “Scrimshawing,” or drawing upon whale’s teeth, also helps to while away many weary hours when the ship lies still in a tropic calm. [Illustration: Cutting away the “junk” from the “case” of a sperm whale. The junk is a mass of cellular tissue which also contains spermaceti. ] The sperm whale is a lover of warm currents which favor the giant squid and cuttlefish on which it lives, and although it has been taken as far north as the Aleutian Islands, Alaska, even there it is in the comparatively warm waters of the Japanese stream; it has also been captured in the sub-Antarctic near the Falkland Islands. The squid reach a length of twenty feet or more and the whale sometimes has terrific battles with its huge prey, the tentacles of which, armed with deadly suckers, tear long gashes in the skin of the head and snout, leaving white scars crisscrossed in every direction. In Japan I took several enormous spiny lobsters from the stomach of a sperm whale, as well as the remains of a shark and seventy or eighty yellow parrot-like beaks of the cuttlefish. Unlike the whalebone whales, of which the opposite is true, the male sperm is very much larger than the female, and an old bull will sometimes reach a length of seventy feet and weigh eighty or ninety tons. Such an animal is a truly colossal creature. The head of a sixty-foot sperm, which was killed by Captain Fred Olsen in Japan especially for the American Museum, was almost twenty feet in length, and the skull, when crated, had a space measurement of twenty-six tons; it was so large that it would barely pass through the main hatch of the steamship which carried it to New York.