SUBBRACH1AN MALACOPTERYGIANS. 213 



The second family of Subbrachian Malacopterygians, commonly called, 



FAMILY II. 



FLAT-FISHES, 



Comprises the great genus 



Pleuronectes*, Lin. 



These fishes present a character which is perfectly unique amongst 

 vertebrated animals: it is the total want of symmetry in the head, where 

 both eyes are on one side, which always remains uppermost when the ani- 

 mal is swimming ; and which is always deeply coloured, while that on 

 which the eyes are wanting is always whitish. The remainder of the 

 body, although, generally speaking, formed as usual, participates a little 

 in this irregularity. Thus the two sides of the mouth are not equal, and 

 the two pectorals are rarely so. Their body is strongly compressed and 

 vertically elevated; the dorsal extends along the whole back; the anal 

 occupies the under part of the body, and almost seems to be continued 

 forwards by the ventrals, which are frequently united with it. There are 

 six rays in the branchiae. The abdominal cavity is small, but is prolonged 

 by a sinus, which penetrates into the thickness of both sides of the tail, 

 for the purpose of lodging a portion of the viscera. The natatory blad- 

 der is wanting, and they seldom quit the bottom. The cranium is ren- 

 dered an object of curiosity by this subversion, which throws both orbits 

 on one side; all the bones, however, common to other genera, are found 

 in it, but unequally proportioned. They are taken along the coasts of al- 

 most all countries, and furnish a wholesome and delicious article of food. 



Individuals are sometimes captured whose eyes are placed on the side 

 opposite to that in which they are generally seen, they are then said to 

 be contournes, or turned; others, again, have both sides of the body co- 

 loured alike, when they are called doubles or doubled; it is most gene- 

 rally the brown side which is thus reproduced, though it sometimes hap- 

 pens to the white one*j\ We divide them as follows: 



Platessa, Cuv. t 



The Plaices have a range of obtuse trenchant teeth in each jaw, and, 

 generally, teeth as if paved in the pharyngeals; the dorsal extending no 

 farther than to above the upper eye, and leaving, as does the anal, a naked 

 interval between it and the caudal. The form of these fishes is rhom- 

 boidal, and most of them have their eyes on the right; they have two or 

 three small caeca. Several species are found in the seas of Europe, 

 such as, 



* Pleuronecles, a name formed by Artedi, from pleura, the flank, and nektes, a swim- 

 mer, because they swim on the side. The antients gave them different names ac- 

 cording to the species, such as Passer, Rhombus, Buglossa, &c. 



f The Rose-cofourtd Flounder, Shaw, IV, ii, pi. 43, is one of those in which the 

 white side is doubled. 



