i6 CLASSIFICATION OF FISHES. 



body is short and broad : their most essential distinction^ 

 however^ from these latter (-which are much diversified 

 in the aberrant examples) is to be found in the finely 

 crenated margin of the operculum^ and the isolated 

 spines upon the pre-opercule : sometimes both these cha- 

 racters exist in the same genus ; while in others there 

 is only one. The teeth are variable ; but they are 

 generally small^ sharp^ and detached ; usually situated 

 not only in the jaws^ but also on the vomer and palatine 

 bones : the ventral fins are always perfect, of ordinary 

 dimensions and structure ; and they are placed under the 

 pectorals. There is nothing, in short, in the develop- 

 ment of any part of these fishes, which gives a prepon- 

 derance of power to any one part, and a corresponding 

 weakness or diminution to another. They are perfectly- 

 shaped fishes, with the two dorsal fins either very dis- 

 tinct, or shghtly connected. The number of rays in the 

 gill membrane is generally seven ; but this character, to 

 which so much importance has been attached, we con- 

 sider as of a very secondary nature. We arrange the 

 whole of this group under five sub-families ; the names 

 of which, as usual, are taken from the genera which 

 appear to be the types; viz. — 1. PercincB ; 2. Sera- 

 nince; S. FercopMncE ; 4. HolocentrincB ; and 5. Helo- 

 tincE. "We shall only notice the genera of the first of 

 these, as that wiU be sufficient to give the reader an in- 

 sight into the principles of arrangement, according to 

 the natural affinities, which have guided us in all the 

 others. 



(14.) The Percina, or true perches, have the two 

 dorsal fins generally separated : the membrane which 

 connects the rays is semi-transparent, and shghtly, if at 

 aU, coloured, as in the beautiful group which next suc- 

 ceeds, namely, the SerranincB. The form of the body 

 in the perches is oblong; the scales comparatively large, 

 but without extending over the dorsal fins: the pectorals 

 and ventrals are obtuse, and somewhat rounded ; the 

 mouth large, and furnished with short, small^ and 



