Flounder, a flat fish of the family pleuro-nectidae or planidae, which also includes the halibut, sole, and turbot. This family, containing about 150 species, is found generally in comparatively shallow water, where the bottom is sandy; but the halibut and turbot are caught in deep water. The body is flat, compressed vertically, so that the dorsal and ventral surfaces are mere fin-bearing edges, the sides forming ovate disks variously colored, the darker being popularly called the back and the white side the belly, while in reality these sur-faces are the sides. The most remarkable character of the family is the want of symmetry in the mouth and head, both eyes being turned to that side which is uppermost when the animal swims, and which is always the darker; the bones of the head, especially the presphe-noid and the middle frontal, are distorted to allow this arrangement of the parts; behind the scapular arch there is no want of symmetry in the vertebral column. The dorsal tin fringes the whole back, from near the tail to as far forward as the nostrils, the anal fringing the lower edge in a similar manner; the jaws and the ventrals are generally unsymmetrical, the latter being smaller on the pale side.
The branchiostegal rays are six; the air bladder is absent, and the vent is very far forward.-The flounder belongs to the genusplatessa (Cuv.); in this the eyes are generally on the right side, one above the other; the teeth are broad and cutting, and in a single series in the jaws, but generally pavement-like on the pharyngeals; the dorsal commences over the upper eye, and neither it nor the anal extends to the caudal; there are three pancreatic ca?ca. The common flounder of Massachusetts (P plana, Mitch.) varies in length from 10 to 22 in., and in color (on the right side) from dull slate to rusty and blackish brown; the scales are small, and the surface smooth. This species is considered excellent for the table in summer and autumn, and is caught in considerable numbers from wharves and bridges. Another species is the rusty dab (P. ferruginea, Storer), from 12 to 20 in. long, of a reddish slate color, with rusty spots, and the lower surface tinged with yellow. The New York flounder is the P. dentata (Mitch.), reddish brown, of about the same size, but considered inferior for the table. Among the species with eyes on the left side are the P. ob--longa (Mitch.), growing to a length of 30 in., and the P. stellata (Pallas), an arctic flounder, of a liver-brown color, about a foot long.
These species are said to be "reversed" when the eves are on the left side in the first series, and on the right in the second; they are said to be "doubled when both sides are colored;
American Flounder Platessa plana).
! according to De Kay, tho P. melanogaster (Mitch.) is a doubled variety of the P. dentata.
Flounders extend, though in diminished numbers and of smaller size, into high northern latitudes: they are very abundant on the coasts of New Brunswick and Nova Scotia in summer. Like all the family, flounders are very tenacious of life, may be transported considerable distances, and may be naturalized in brackish and even in fresh water. The distortion of the flounder family admirably adapts them for swimming on the bottom, where the situation of both eyes on the upper surface of the head allows an extensive range of vision; the coloration of one side, resembling the bottom on which they swim, serves as a protection against enemies. The food consists of minnows and other small fry, young fish, soft-bodied marine animals, and aquatic insects. There are 16 species in the British islands, which are gradually reduced to 13 in the Baltic, 10 on the coast of Norway, 5 at Iceland, and 3 in Greenland. The English plaice (P. vulgaris, Flem.), called also fluke in Scotland, is much esteemed; the spawning time is in February or March, and it is in the best condi-tion for the table at the end of May. The English flounder is the P.flesus (Flem.). and may be distinguished from the plaice by the rough lateral line.
The common dab (P. limanda, Flem.) derives the specific name from the roughness of its scaly surface, and. with other species, is considered excellent; they are taken by hook, spear, and net.
English Flounder (Platessa flesus).