MAMMALIA. 427 



The genu^ Phocama^ Porpoises, is easily recognisable by tlie shortness 

 of the snout, which can scarcely be distinguished from the forehead. The 

 jaws, however, are elongated, and very distinct from the skull when the 

 soft parts are removed, which in the living condition give to the head and 

 snout that roundness which distinguishes this genus. The porpoises live 

 associated in large numbers, and sometimes ascend rivers far from the sea. 

 Their food consists of tishes and molluscs, which they consume in large 

 quantities. P. communis is the most common species met with in the 

 European seas, and is often caught by fishermen. A species very much 

 related to it, and with whicli it has been confounded until very lately, is 

 peculiar to the American shore of the Atlantic (P. americana). It differs 

 from the former in having the teeth grooved on the broad faces near the 

 summit, so as nearly to divide them into three lobes, whilst in P. communis 

 they are smooth. The dorsal fin is serrated and tuberculous. The largest 

 species of this genus, the common grampus, P. orca (with some authors 

 Orca communis), measures from twenty to twenty-four feet in length, with 

 a body of proportional bulk. The snout is very short, the dorsal fin very 

 high, the teeth large and in small number, eleven in each side of both jaws, 

 conical and a little bent backwards. Those near the extremity of the lower 

 jaw are worn otf first. The upper part of the body is black, the lower white, 

 and a white oblong spot above the eyes. Found in the Mediterranean and the 

 Atlantic. The P. gladiator, or sword grampus, is remarkable for its dorsal 

 fin, which is higher than the body itself under it. The skull is vaulted, the 

 snout depressed, very obtuse, and the lower jaw a little longer than the 

 upper one. This species lives in Davis's Straits, on the coasts of America 

 and Spitzbergcn, in troops of from six to eight. The P. glohicejjs, also large 

 and bulky, has a snout still shorter and more rounded, and a large triangular 

 dorsal. The number of teeth varies very much ; in adult specimens each 

 jaw has from eighteen to twenty-six of them. Their form is conical, 

 slightly curved inwards at their tip. This species keeps the open seas, but 

 was once seen at the mouth of Charles River, between Boston and Charles- 

 town (Mass.). A similar species, P. rissoana, is found in the Mediterranean, 

 and has a snout still shorter, a character which has led some naturalists to 

 place it in a special genus, Glohiceplialus, which included those jjorpoises 

 with a round and more or less spheroidal head. Some other species of 

 Phocffina are described in systematic works. 



The genus Delphinapterus includes only one species as far as known, the 

 beluga or white whale, whose characters consist in the absence of a dorsal 

 fin, instead of which it has only a kind of longitudinal projection on the 

 back. The head is proportionally small, spheroidal, and the snout truncated, 

 or rather rounded off. Both jaws are equal, and furnished with nine or ten 

 small teeth, blunt at the top, but unequal and distinct from each other. 

 The D. beluga is a native of the northern seas, the Arctic, and esjiecially 

 of Hudson's Bay and Davis's Straits. 



The genus Oxypterus is known only from vague information. Rafinesque 

 established it for a species from the seas of Sicily, calling it 0. mongitori. 

 According to Quoi and Gaimard (Voyage de I'Uranie, Zool., p. 86, pi. ii., 



631 



