160 BULLETIN OF THE BUREAU OF FISHERIES 



reappear there in October and later. This seasonal cycle is just the reverse of what 

 obtains in the North Sea region, where Euthemisto compressa occurs commonly in 

 winter with the indraught of Atlantic water (Tesch. 1911), but only in small numbers 

 at other seasons. 



The presence of adults with eggs, of larvae, and of immature specimens at various 

 stages in development shows that Euthemisto 87 breeds successfully over the entire 

 area of the Gulf of Maine outside the outer islands and headlands — perhaps even in 

 Massachusetts Bay. Large numbers of young are sometimes produced in the inner 

 parts of the gulf — for instance, the swarms of young off Penobscot Bay in August, 

 1913, mentioned above (p. 20) — as well as in the surface waters of the western basin, 

 where newly hatched as well as medium-sized Euthemisto were plentiful on August 

 31, 1915 (station 10307). The chief breeding areas, as indicated by relative abun- 

 dance, lie over the outer edge of the continental shelf, extending as far west at least 

 as longitude 71°, where we found shoals of young specimens as well as of adults late 

 in August in 1913 (Bigelow, 1915, p. 281); likewise on the central, northwestern, and 

 southwestern parts of Georges Bank, on Browns Bank, and in the coastal waters 

 off Cape Sable. In this general zone we have not only found breeding adults as 

 well as young on many occasions, but more than once have taken young in abundance 

 on the surface and adults with eggs in the deeper hauls (p. 163). 



The breeding season of Euthemisto certainly extends over a large part of the 

 year, for we have found its larvae in every month from February until October. 

 Probably it also breeds during the late autumn, when we have not visited its chief 

 offshore areas of reproduction, for occasional young specimens appeared in our 

 tows near the Isles of Shoals and off Cape Cod in the first week in November, 1916 

 (stations 10400 and 10403), and in the deep near Cape Ann late in December, 1920 

 (station 103S9) ; but young are produced in greatest number in June, July, and 

 August. 



No attempt has yet been made to estimate the actual numerical strength of 

 Euthemisto in the Gulf of Maine, but at times the local population must be con- 

 siderable to yield the abundant tow-net catches mentioned above (p. 156). 



In the preceding lines the genus has been treated as a unit. The relative 

 fluctuations of its two local representatives, the species compressa and bispinosa,** 

 are next to be considered. Although these two species of Euthemisto are often 

 taken side by side, they occupy somewhat different faunal niches, with bispinosa 

 the more oceanic of the two and showing a more definite seasonal movement toward 

 and away from the coast than compressa does. 89 During the period February to 

 May, when the genus as a whole is at a low ebb in the Gulf, compressa is decidedly 

 the commoner member of the pair in its inner waters, while on Georges Bank and 

 south of Nova Scotia the two occur in roughly equal numbers at that season (at 

 least such was the case in 1920). In June, when the numbers of the genus as a 

 whole increase, compressa still predominates within the gulf, but we found bispinosa 



87 Both E. compressa and E. bispinosa. 



t» For descriptions and the distinguishing features of these two see Sars, 1895. I have elsewhere given tables of the relative 

 abundance of the two for several of our cruises (Bigelow, 1914a, p. 4; 1915, p. 279; 1917, p. 287; 1922, pp. 133 and 148). 



•• For tables of the relative abundance of the two species of Euthemisto from 1913 to 1915 see Bigelow, 1915, p. 282, and Bigelow 

 1917, pp. 287 and 288. 



