Fam. 3. Phocidae.—The true Seals have no external ears, and the nostrils are quite dorsal in position as in other aquatic animals, such as the Crocodile. There is obviously an approach to the conditions characteristic of the Whales. The hind-limbs are useless for locomotion on land. They are bound up with the tail, and form functionally merely a part of the tail. In this family there are, at any rate, eight genera.
Fig. 230.—Common Seal. Phoca vitulina. × ⅛. (From Parker and Haswell's Zoology.)
Phoca and Halichoerus are not very wide apart from each other. In both there are five well-developed claws on feet and hands. They are British, and generally Arctic and temperate in range. For some reason or other the late Dr. Gray placed Halichoerus in the same sub-family with the Walrus! Phoca is not only marine, but is found in the Caspian and in Lake Baikal. Their existence in those inland seas is believed to be a vestige of a former connexion with the sea. Halichoerus grypus is a large seal 8 feet in length when full grown. Its colour is yellowish grey, with darker grey spots and blotches. It is not uncommon on the shores of our islands, particularly of the Hebrides and Argyllshire. The commonest Seal is Phoca vitulina, not more than 4 to 5 feet long, and of the same spotted coloration as the last. This Seal has, however, a much wider distribution, being Arctic as well as British, American, and North Pacific. A curious fact about this Seal is that it is not impatient of fresh water; not only will it ascend rivers, but it will live in inland lakes. It is said to be especially sensitive to musical sounds. P. hispida is British, but a rare visitor to our islands. It is essentially an Arctic species. The Harp Seal, P. groenlandica, is so called on account of a harp-shaped black bar in the males, which starts at
