Page:Natural History, Fishes.djvu/71

Rh differ considerably in subordinate points. Five leading types are seen to subsist, around which so many groups, called Sub-Families, are arranged. These we shall briefly notice.

The true Perches (Percina) have two distinct dorsal fins, with the membrane which connects the rays semi-transparent and nearly colourless. The pectorals and ventrals are obtuse, or somewhat rounded; the former contain each five soft rays; the latter are placed beneath the pectorals. The form of the body is oblong; the scales are comparatively large; the mouth is wide, and furnished with short and small teeth much crowded, without any larger pointed teeth, resembling canines, at the sides. The genus Lucioperca, as its name, signifying Pike-perch, expresses, has the structure of a Perch with the form and appearance, and even the ferocity of a Pike; while the Diploprion, of the coast of Java, and still more the Enoplosus of Australia, might readily be mistaken for a true Chætodon, having not only the short, high, compressed form of that genus, with its tall fins, but the small mouth, and delicate teeth, and even the characteristic colours and markings of Chætodon, the former being yellow, with a black vertical band through the eye, and another across the body, and the latter silvery white, with seven or eight vertical bands. Yet in each case the fins are destitute of scales, the gill-plates are spinous, and all the essential characters of true Perches, are exhibited.

The Serrans (Serranina), a very numerous sub-family, are distinguished by having the two dorsals united into a single fin, the place of the division being marked, however, by a depression