FLOUNDER, a common term for flat-fish. The name is also more specially given to certain varieties, according to local usage. Thus the Pleuronectes flesus is the common flounder of English terminology, found along the coasts of northern Europe from the Bristol Channel to Iceland. It is particularly partial to fresh water, ascending the Rhine as far as Cologne. It rarely exceeds a length of 12 in. or a weight of 1 lb In American terminology the principal fish of the name are the "summer flounders" or "deep-sea flounders," also known in America as "plaice" (Paralichthys dentatus), as long as 3 ft. and as heavy as 15 lb; the "four-spotted flounders" (Paralichthys oblongus); the "common" or "winter" flounder (Pseudopleuronectes americanus); the "diamond flounder" (Hysopsetta guttulata); and the "pole flounder" (Glyptocephalus cynoglossus).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)