56 ACANTHOPTERYGII. — PERCAD^. 



Family I. Percad^. 



(Perches.) 



A vast assemblage of species, amounting to 

 about one-seventh of the whole Class, is seen by 

 the preceding table to be comprised in this 

 Family. They are, for the most part, marine 

 fishes, though the typical genus, which gives a 

 name to the Family, inhabits fresh waters. The 

 form is generally long-oval ; the body is covered 

 with scales, the surface of which is more or less 

 rough, and the free margins of which are notched 

 like the teeth of a comb ; the scales do not ex- 

 tend upon the fins ; the gill-cover (operculum), and 

 the gill-flap (preoperculum), are variously armed 

 with spines, and cut into teeth at their margins. 

 Both the upper and lower jaw are set with teeth, 

 besides which, the bones of the palate and the vomer 

 (or middle ridge of the roof of the mouth) are 

 furnished with them, so that there are five rows 

 of teeth above, and two below. In general, all the 

 teeth are fine, and set in close array, so as to bear 

 a remote resemblance, in appearance, to the pile of 

 velvet. The hranchiostegous rays^ or the slender 

 arched bones of the membrane that closes the 

 great fissure of the gills beneath, vary in number 

 from five to seven. The ventral fins are, in 

 general, placed under the pectorals ; the dorsal is 

 either double or depressed in the middle. 



So immense a Family cannot but comprise 

 several varieties of form, which, while agreeing 

 in the important characteristics that distinguish 

 these Fishes from those of the other Families, 



