Sea-snakes (_Hydrophis_) are found on all the coasts of Ceylon. I have sailed through large shoals of them in the Gulf of Manaar, close to the pearl-banks of Aripo. The fishermen of Calpentyn on the west live in perpetual dread of them, and believe their bite to be fatal. In the course of an attempt which was recently made to place a lighthouse on the great rocks of the south-east coast, known by seamen as the Basses[1], or _Baxos_, the workmen who first landed found the portion of the surface liable to be covered by the tides, honeycombed, and hollowed into deep holes filled with water, in which were abundance of fishes and some molluscs. Some of these cavities also contained sea-snakes from four to five feet long, which were described as having the head "hooded like the cobra de capello, and of a light grey colour, slightly speckled. They coiled themselves like serpents on land, and darted at poles thrust in among them. The Singhalese who accompanied the party, said that they not only bit venomously, but crushed the limb of any intruder in their coils."[2] [Footnote 1: The Basses are believed to be the remnants of the great island of Giri, swallowed up by the sea.--_Mahawanso_, ch. i. p. 4. They may possibly be the _Bassæ_ of Ptolemy's map of _Taprobane_.] [Footnote 2: Official Report to the Governor of Ceylon.] Still, sea-snakes, though well-known to the natives, are not abundant round Ceylon, as compared with their numbers in other places. Their principal habitat is the ocean between the southern shores of China and the northern coast of New Holland; and their western limit appears to be about the longitude of Cape Comorin. It has long since been ascertained that they frequent the seas that separate the islands of the Pacific; but they have never yet been found in the Atlantic, nor even on the western shores of tropical America. And if, as has been stated[1], they have been seen on a late occasion in considerable numbers in the Bay of Panama, the fact can only be regarded as one of the rare instances, in which a change in the primary distribution of a race of animals has occurred, either by an active or a passive immigration. Being exclusively inhabitants of the sea, they are liable to be swept along by the influence of currents; but to compensate for this they have been endowed with a wonderful power of swimming. The individuals of all the groups of terrestrial serpents are observed to be possessed of this faculty to a greater or a less degree; and they can swim for a certain distance without having any organs specially modified for the purpose; except, perhaps, the lung, which is a long sac capable of taking in a sufficient quantity of air, to keep the body of the snake above water. Nor do we find any peculiar or specially adapted organs even in the freshwater-snakes, although they can catch frogs or fishes while swimming. But in the _hydrophids_, which are permanent inhabitants of