HIPPOPOTAMUS

(Yunanca köken — orijinale bakınız.) A genus of aquatic Pachyderms, represented at the present time by a single species (Hippopotamus amphibius, L.) which inhabits the rivers of Africa. The generic characters are four toes on all the feet, inclosed in small hoofs; six molar teeth on each side of both jaws; very large and strong canines, of which the upper 557 HISPID. ones are nearly straight, the lower ones curved, and work* ing upon each other so as to produce a chisel -edge; four incisors in each jaw, the upper ones short and conical, and bent inwards towards the mouth; the under ones long, cylindrical, and pointing forwards. The hippopotamus lives during the daytime immerged in the waters of its native rivers, rising to the surface and protruding its nostrils for the purpose of breathing: it comes to the land to feed during the night. Remains of species ot hippopotamus are found in the tertiary formations of Europe, one of which hardlv exceeded the size of a hog. In the tertiary beds at the base of the Himalaya range, an extinct species of hippopotamus has been discovered which had six incisor teeth in each jaw. HPPPOPUS. {Gr. Strfrof, a horse, • vevs, a foot.) The name of a genus of Acephalous Mollusks, significative of the resemblance which their shell bears to the foot of a horse. The valves of this shell are equal, regular, but in equilateral and transverse; the hinge has two compre ed unequal teeth; the ligament is marginal and external. The Hippopi belong to the family TridacnidUB of the Lamarchian system; but are distinguished from the genus Trtdacna, by having the posterior slope and lunule closed, or nearly so, and the inner margin dentated at that part. The spines which arm the ribs are tubular, and are never arched orva ulted. The type of the genus is the Hippopus maculatus, or spotted hippopus; the lEstrea htppopus of Linnaeus. [s. 570]