56 
ACANTHOPTERYGII. — PERCAD^. 
Family L 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 gilhfiap {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, 
