I. See Walrus. II. An osseous fish of the order lophobranchs (with tufted gills), of the family of pipe fishes, and of the genus hippocampus (Cuv.). The ordinal and family characters have been described in the articles Lophobeanchs and Pipe Fish. In the present genus, which includes several species, the snout is prolonged and the head elevated posteriorly, somewhat resembling a miniature horse's head, the ears being represented by a spiny coronet on the occiput; the orbits, pectoral ring, and the other rings of the mailed body are more or less spiny; the tail is without a fin and prehensile, and by means of it they suspend themselves to sea weeds and other submarine objects; the eyes are prominent, and can be moved independently of each other, and in opposite directions; the pouch in which the males carry the eggs till they are hatched opens at the commencement of the tail; the ventrals are absent, and the pectorals very small and just behind the head; there is a single short dorsal on the middle of the back, whose edge has a spiral motion; the females have a small anal; the mouth is terminal and without teeth.

They inhabit all parts of the temperate and especially of the tropical oceans; the food consists of minute marine animals, especially ova; a kind of hibernation has been observed in the Mediterranean species by Rusconi; they swim vertically, with the tail ready to wind around any object they meet. There is one species in the British seas, the H. brevirostris (Cuv.), 6 in. or more in length, with much compressed, short, and deep body, divided by longitudinal and transverse ridges, with tubercles at the line of intersection; the snout is comparatively short; the color is pale ashy brown, with iridescent tints about the head. De Kay describes the H. Hudsonius, 3 to 6 in. long, from the coast of S. New England and New York; it is yellowish brown, with 12 rings in the body and 36 in the tail. Other species are found in the Mediterranean, and more abundantly in the East Indies.

Sea Horse (Hippocampus brevirostris).

Sea Horse (Hippocampus brevirostris).