on the under side of the head, and is furnished with teeth which are adapted to crushing crustaceans and similar creatures upon which they feed, and not for tearing flesh. Behind the eyes they have two large blow-holes.
The common saw-fish reaches a length of twelve to fifteen feet, of which the saw is about one third. It carries a much uglier weapon than the sword-fish, for along the edges of its beak are set pointed conical teeth, two or three inches apart. The number of teeth on each side varies from twenty to thirty. The "saw" is not used by being drawn backward and forward: in killing small fishes for food, the saw-fish charges among them, striking to the right and left with the serrated edges of its beak, and generally succeeds in disabling a considerable number. When a whale is the creature attacked, this terrible weapon is plunged into the soft, blubber-covered body of the cetacean, the saw-fish avoiding by superior agility the strokes of the tortured animal's tail, any one of which would end the career of the daring gladiator. His weapon is often found deeply imbedded in the side of a ship, and even after the death of its original owner the beak may still inflict grievous wounds, for the Polynesians are fond of using it as a sword.
The narwhal belongs to the order of whales, and hence is not a fish. When full grown it reaches a length of about sixteen feet; it has the rounded body and horizontally flattened tail of the whales, but its head is small and rounded more like that of the seal. It inhabits the Arctic seas, and is a valuable game for the Greenlanders, as its flesh is much prized by them, and it yields a moderate quantity of very delicate oil. The color of its skin is gray, varied by darker streaks and patches, and shading from almost black above to white underneath. The curious horn to which the narwhal owes its fame is not a prolongation of the jaw as in the case of the fishes just described, but is a long tooth, like the tusks of the elephant or the boar. In the upper jaw of the young narwhal are found two small tusks, which in the female regularly remain undeveloped throughout her life. In the male the left tusk grows into a spirally grooved rod, sometimes attaining the length of ten feet. A large narwhal's tusk has no small commercial value, for the. ivory is very hard and solid, will take a high polish, and keeps its beautiful whiteness a long time. Several ingenious speculations have been made in regard to the use of this remarkable growth; killing fish for food and breaking breathing-holes through the ice are two uses suggested which fail to account for the long tusk being confined to the males. The females certainly can not live on air alone, nor without air, and they can not count on always having a male near to wait upon them. It is more probably to be accounted for by the same reasons which explain the possession of horns, tusks, or mane by the males only of some land mammals. Rarely the right tusk is developed instead of the left, and sometimes the female has a weapon
