The only one of these that we can mention is the Gangetic dolphin, which inhabits the great rivers of India, and is named from the Ganges. Its chief peculiarity is that it is almost totally blind. Although the animal grows to a length of seven or eight feet, and is bulky in proportion, yet its eyeballs are no larger than peas, while the nerves of sight are so imperfect that it is quite possible that it may not be able to see at all. This is no deprivation to it however, for the rivers in which it lives are always so thick with mud that even if it had properly developed eyes it would be quite unable to use them. The Gangetic dolphin is very seldom seen, because when it comes up to breathe it only raises just the blow-holes above the surface of the water. For the same reason, we know very little indeed about its habits. But it seems to feed on fresh-water shrimps and mollusks, and also on certain fishes which lie half-buried in the mud at the bottom of the water, rooting about for them with its snout after the manner of a pig. This animal is often known as the susu. SEA-DOLPHINS Of the sea-dolphins we can only notice two. The first of these is the common dolphin, which is found in great numbers in almost all parts of the temperate and tropical seas. Apparently it is not often to be found on American coasts, but it has been captured in eastern harbors. It generally lives in herds, which will follow ships for hours together, leaping and gamboling on the surface of the sea, and yet keeping pace with the vessel without the least apparent effort. It feeds on fishes, to capture which, and hold them firmly, it has one hundred and ninety teeth, so arranged that when the mouth is closed the upper and lower ones fit in between one another like those of a steel trap and hold the prey in a grip from which there is no escape. A full-grown dolphin is usually about seven feet long, but much larger specimens are occasionally found. The color is dark gray or glossy black above, and almost pure white on the lower parts of the body. The bottle-nosed dolphin is a rather smaller animal, with a shorter and more pointed beak shaped rather like the neck of a bottle, and is purple black above and grayish white below. Its range is on the North Atlantic coast from Maine to Florida, on the Gulf coast, and also on some of the coasts of Europe. MANATEES AND DUGONGS There is just one other family of water-mammals which it will be convenient to mention here, although they do not really belong to the whale tribe. These are the very curious creatures known as sirenians, the best known of them being the manatee and the dugong.