The serpent race, which thrives so abundantly in the tropical forests and morasses, has also its marine representatives in the Indian and Pacific Oceans, where more than fifty species of Hydrophis, Pelamys, and Chersydra have been found. They are distinguished from their terrestrial relations by the flattened form of their tail, the planes of which being directed vertically give it the properties of a powerful oar, in striking the water by lateral oscillations. These sea-snakes always appear to prefer calms, swimming on the still surface in an undulating manner, never raising the head much from the surface, or vaulting out of the water. They dive with facility on the approach of danger, but do not appear to be particularly timid. [Illustration: Water-Snake.] The Pelamys bicolor is very common from India to Otaheite. In the seas of Mindoro and Sooloo, Mr. Adams saw thousands swimming on the top of the water, especially in eddies and tide-ways where the ripple collects numerous fish and medusæ, which principally constitute their prey. Their tongue is white and forked, differing in respect of its colour from the tongue of other snakes, which is generally black. The water-snakes, which are frequently beautifully banded, and as thick as a man's leg, are said to be highly venomous. Captain Cook, in one of his voyages, "saw abundance of water-snakes, one of which was coming up the side of our ship, and our men beat it off. The Spaniards affirm there is no cure for such as are bit by them; and one of our blacks happened to fall under that misfortune, and died notwithstanding the utmost care was taken by our surgeons to recover him." Such are the _real_ sea-snakes as they are met with by ordinary travellers, while _the great sea-serpent_, which from time to time dives up in the columns of the newspapers, must, until better evidence be brought forward for its existence, be banished to those dim regions peopled by unicorns, griffins, krakens, and tailed men. Olaus Magnus, it is true, speaks of the great sea-snake as if it made its daily appearance on the Norwegian coast. According to him, it inhabits the rocky caves near Bergen, and wanders forth at night, particularly by moonshine, to commit its depredations by sea and land; as calves and pigs seem to suit its appetite as well as fishes and lobsters. The body is covered with scales, a long mane flows along the neck, and the head, furnished with two glistening eyes, rises like a mast out of the water. It often attacks ships, and picks up seamen from the deck. This description may serve as an example of the boldness with which authors have sometimes asserted the most extravagant things.