platessoidejE. 255 



PLATESSOIDE.E.— FLAT FISH. 



The fish of this family were included by Linnseus in a single large genus, which 

 was named pleuronectes by Artedi, to denote their peculiar habit of swimming on 

 one side. They have, in fact, a character of which there is no example in any 

 other family of vertebrated animals, that of both eyes being on the same side of the 

 head, which is the uppermost when the fish swims, and is more or less deeply 

 coloured, while the other side is always whitish. The orifice of the mouth is 

 oblique, with unequal sides, and the greatly compressed body partakes more or less 

 of the want of symmetry observable in the head ; the pectorals are seldom uniform, 

 the dorsal occupies the whole length of the back, the anal fringes the under edge 

 of the body, and the ventrals, which are often joined to one another, appear like an 

 anterior continuation of it. There are six gill-rays. The abdominal cavity, which 

 is small, is prolonged into the substance of the tail to give room for the lodgment 

 of the viscera, the anus being far forward. The cranium is composed of the ordi- 

 nary number of bones, though their forms are curious, owing to both the orbits 

 being on one side. There is no air-bladder, and these fish seldom leave the bot- 

 tom. The latter circumstance may account for the fish of this family being found 

 in all climates, the temperature of the bottom of the ocean being comparatively 

 equable. The Flat fish yield a wholesome and agreeable article of diet to the in- 

 habitants of every coast. The following are reported to inhabit the seas of the 

 United States ; but as many of them have been very imperfectly described, it is not 

 certain whether they are all proper species, or even rightly referred to the sub- 

 genera. PlatessjE. — Pleuronectes dentatus, Summer flounder. Linn., Schoepf, 

 Mitchill ; Pleur. Americanus, Schn. (Rhode Island flounder, Schoepf) ; 

 Pleur.melanogaster, Black-bellied flounder, Mitchill; Pleur. oblongus, Spotted 

 flounder, Mitchill. Hippoglossi. — Pleur. hippoglossus, Halibut, Schoepf, 

 Penn., Mitch., Smith. Rhombi. — Pleur. argus vel lineatus, Bloch, Catesby ; 

 Rhombus maximus, Turbot, Smith. Sole^e. — Sole, Pleur. solen, Penn. (Solea 

 vulgaris, Smith). Achiri. — Pleur. lineatus, Linn. {Pleur. mollis, New York 

 sole, Mitch.) ; Pleur. plagiusa, Garden, Linn. 



It is highly probable that many of the above extend their range to the British 

 American coasts. La Hontan mentions " plies et turbots comme en Europe" as 

 frequenting the embouchure of the St. Lawrence, and Pennant enumerates the 



