248 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



as an opah by the included description and sketch, 

 had been landed in Portland, Maine, from the 

 Grand Banks. 16 



One was caught off Sable Island, Nova Scotia, 

 about 1856, and another off La Have Bank many at Hyamiis, Mass., on September 17, 1928. 18 



years ago; l8 a specimen about 3 feet long was 

 taken in July 1925 on Western Bank, southwest 

 of Sable Island, by the schooner Falmouth; 17 and 

 another of the same size stranded on the beach 



THE FLOUNDERS AND SOLES. FAMILIES HIPPOGLOSSIDAE, PARALICHTHYIDAE, 

 PLEURONECTIDAE, BOTHIDAE, AND ACHIRIDAE 



The flatfishes are a very homogenous tribe, 

 so different from all other fishes that no one is 

 likely to mistake any one of them for any other 

 sort of fish. What strikes one first is their flatness ; 

 less obvious is the fact that they do not lie on the 

 belly but on one side, right or left. And their 

 skull twists in the course of development so that 

 the eye which was originally on the side that is 

 fated to be underneath, migrates around the head, 

 until both the eyes finally come to lie close to- 

 gether, on the side that is uppermost as the fish 

 lies on bottom. But the mouth retains its origi- 

 nal position more nearly, so that it is often de- 

 scribed as opening sidewise. The larval flounder 

 swims on edge like any other fish; the migration 

 of the eye takes place shortly before the fry take 

 to the bottom. 



All of the flatfishes have a single long fin on 



each edge, one the dorsal and the other the anal; 

 they also have well-developed ventral fins (at 

 least on the eyed side) which are either on the 

 right-hand edge or on the left-hand edge as the 

 fish lies. Most of the Gulf of Maine species also 

 have pectoral fins, one on the upper side as the 

 fish lies on the bottom, the other on the lower 

 side. The ventral fins are in front of the pectorals 

 or in line with them; the abdominal cavity is 

 very short, and some species are armed with a 

 stout anal spine. 



Our several flatfishes look much alike; indeed, 

 they are often confused. But it is not difficult 

 to tell one from another, for the distinctive char- 

 acters are rather precise, even if not obvious at 

 first glance. Huntsman 19 has published a very 

 useful key to the eastern Canadian species, which 

 is expanded here to cover the Gulf of Maine. 



KEY TO GULF OF MAINE FLATFISHES 



1 . Eyes on the left-hand side, and guts at left-hand edge, as the fish lies on bottom 2 



Eyes on the right-hand side, and guts at right-hand edge 5 



2. The lateral line is straight Citharichlhys arctifrons, p. 294 



The lateral line is arched over the pectoral fin 20 3 



3. The two ventrals are not alike, the left (upper) being continuous with the anal fin, the rirrht (lower) separate from 



it Sand flounder, p. 290 



The two ventral fins are alike 4 



4. The upper side is marked with four large oblong black eye-spots: there are fewer than 82 rays in the long right-hand 



(dorsal) fin Four-spotted flounder, p. 270 



The upper side is marked with many small spots; there are more than 84 rays in the long right-hand (dorsal) fin 



Summer flounder, p. 267 



5. There is a well-developed pectoral fin on the eyed side 6 



There are no pectoral fins Hog choker, p. 296 



6. Mouth large, gaping back as far as the eye; jaws and teeth nearly equally developed on both sides 7 



Mouth small, not gaping back as far as the eye; the jaws are nearly straight on the upper side, but curved on the 



lower side 9 



7. Margin of tail fin rounded American dab, or plaice, p. 259 



Margin of tail fin slightly concave, with angular corners 8 



8. Lateral line arched close behind the gill opening Halibut, p. 249 



Lateral line nearly straight Greenland halibut, p. 258 



14 We are Indebted to Norman J. Wllimovsky for showing us a copy of 

 this letter. 



'• Vladykov, Proc. Nova Scotia Inst. Scl., vol. 19, 1935, p. 6. 



" Radcllffe, Copela, No. 151, 1926, p. 112. 



>* Reported by Robert Goffln of the Bureau of Fisheries station at Woods 

 Hole, Mass. 



" Our Eastern Fl3t Fishes, Canadian Fisherman, vol 6, No. 6, 1918, 

 pp. 788-790. 



■ In all the flounders of Ihls type so far recorded from the Gulf of Maine 

 both of the pectoral fins are well developed. Should one be taken with no 

 pectoral fin on the blind side it would probably be the deep-water Monolene 

 lartlicauda. 



