FISHES OF THE GULF OF MAINE 499 



hatched through Welsh's industry. Spawning, as he found, commences near 

 Gloucester by the middle of March, and many ripe fish were taken during the last 

 half of April, but the majority were still green as late in the season as May 8 in 1913, 

 though others were already spawned out; and since we have found eggs indistinguish- 

 able from those of the dab in our tow nets in June, July, August, and one even on 

 September 11, and have taken its newly hatched larvae (6 mm. long) off Race Point 

 as late as August 31, spawning must last all summer. The individual females 

 spawn over a considerable period of time, for Welsh found that only a small part 

 of the eggs ripened simultaneously in any given fish. 



The neighborhood of the Isles of Shoals and of Boars Head, where Welsh 

 obtained his ripe fish, is certainly an important spawning ground at 20 to 30 fathoms. 

 Probably the dab breeds over most of the peripheral belt of the Gulf of Maine 

 between the 20 and 50 fathom contours except in the Bay of Fundy, but we have 

 found no eggs over deeper water, and no doubt it spawns as actively on the offshore 

 banks as it does along shore, for although we have not actually found its eggs there 

 we have taken larva? only 7 to 11 mm. long over both the western and eastern parts 

 of Georges Bank 68 ; also near Gloucester and near the tip of Cape Cod, in July 

 and August. 



The dab also spawns on Sable Island Bank, Banquereau Bank, and the New- 

 foundland Banks, for eggs (no doubt of this species) were collected on these grounds 

 by the Canadian Fisheries Expedition in 1915, 89 and, in the other direction, it breeds 

 as far westward as New York, for we towed 88 young larva? (6.5 to 19 mm. long) 

 11 miles off Sandy Hook on August 1, 1913. 



The egg is buoyant, without oil globule, spherical, very transparent, and with 

 a narrow perivitelline space. One hundred eggs measured by Welsh ranged from 

 0.87 to 0.94 mm. in diameter, averaging about 0.9 mm. The surface of the egg is 

 covered with very minute striations, and while alive the germinal disk is of 

 a very pale buff color. Shortly before hatching (which takes place in 5 days at a 

 temperature of 50° to 52°) the embryonic pigment gathers in three groups — one 

 on the head, one in the anal region, and a third half way between the latter and the 

 tip of the tail. Unfortunately the fish which Welsh hatched were accidentally 

 destroyed, so we can not describe the early larval stages. Larva? of 11 mm. are 

 still symmetrical, whereas at 14 mm. the left eye is already visible above the profile 

 of the head, while all the fins are outlined, their rays are present in the final 

 number (76 dorsal and 59 anal in the specimen illustrated), and the mouth is clearly 

 fated to be "small." Thus, when they have reached this stage they show enough 

 of the diagnostic characters of the adult for positive identification. 



The early larval stages of dabs and of winter flounders resemble each other 

 closely. In fact it is probable that some of the young flatfish pictured by A. Agassiz 70 

 as winter flounders were actually dabs. After the fin rays appear, however, their 



11 Station 10059, July 9, 1913; and station 10224, July 23, 1914. 



»' Dannevig (Canadian Fisheries Expedition, 1914-15 (1919), p. 17) refers these provisionally to the European dab, »hich does 

 not occur on the American coast. Its egg is indistinguishable from that of the American species. 



70 Agassiz. Proceedings, American Academy of Arts and Sciences, new series Vol. VI, whole series Vol. XIV, 1S79, PI. IV. 



