FISHES OF THE GULF OF MAINE 521 



176. Gulf Stream flounder (Citharichthys arctifrons Goode)"' 



Jordan and Evermann, 1S96-1900, p. 2683. 



Description.— This little fish is left-handed (eyes on the left side and guts at 

 the left) with a moderately wide mouth gaping back as far as the forward edge of 

 the eye, a nearly straight lateral line, and with both pectoral fins well-developed, 

 though the one on the eyed side is considerably larger than its mate on the blind 

 side. The left ventral fin is on the midline, the right fin a short distance above it 

 on the side, and while these two fins are alike in females, in males the one on the 

 blind side is much the longer of the pair. The body is ovate in outline and very 

 thin. The long fins are of moderate breadth, with the dorsal fin (about 83 rays) 

 originating over the forward margin of the eye and the caudal fin rounded. The 

 scales are so large that there are only about 40 rows of them along the lateral line. 



Fig. 271.— Gulf Stream flounder (.Citharichthys arctifrons) 



This species parallels the summer, four-spotted, and sand flounders (the latter 

 its closest Gulf of Maine ally) in its left-handedness, but it is distinguishable from all 

 of these by the fact that its lateral line is almost straight and likewise by the great 

 disparity in size between the two pectoral fins and by its very large scales. Its 

 narrow form and the fact that none of its dorsal fin rays are branched are further 

 points of distinction between it and the sand flounder, and it is much smaller at 

 maturity than any of the flatfishes common within the Gulf. 



Size. — Kipe females 3}^ to 4 inches in length have been recorded, suggesting 

 that this is about the maximum size. 



'• A second species of this genus ( C. unicornis) may be expected on the outer slope of Georges Bank in depths of 100 fathoms 

 and more, since it has been taken o£f Marthas Vineyard in 115 to 150 fathoms. It is separable from C. arctifrons by the fact that 

 there is a short spine on the eyed side of the head above the upper lip (the head of arctifrons is spineless). Further points of dis- 

 tinction are that unicornis has smaller and more numerous scales (about 60 rows along the lateral line), fewer fin rays (only about 

 T4 dorsal rays), and that its body is "broader" (actually higher). 



We have towed the pelagic larvae of still a third small deep-water flounder (Monolenc sessilicauda) off the seaward slope of 

 Georges Bank (Bulletin, Museum of Comparative Zoology at Harvard College, Vol. LXI, No. 8, 1917, p. 277), and it has been 

 trawled in depths of 100 fathoms and more off Marthas Vineyard and thence westward and southward along the continental 

 slope. It is left-handed like the summer, four-spotted, and sand flounders, with arched lateral line, but it has no pectoral 

 fin on the blind side. For a detailed description of it see Goode and Bean (1896, p. 452). 



