PLANKTON OF THE GULF OF MAINE 19 



surface waters were alive "with young amphipods (Euthemisto) as well as with young 

 stages of Calanus finmarchicus, in the proportion of about one of the former to 

 four of the latter" (fig. 15), off Penobscot Bay and off Mount Desert Island on 

 August 11, 1913 (Bigelow, 1915, p. 274, stations 10091 and 10092); that older Euthe- 

 misto (fig. 16) were plentiful (though not rivaling the copepods) off Cape Ann and in 

 the western basin on August 31, 1915 (stations 10306 and 10307), and at several sta- 

 tions along the outer edge of the offshore banks (p. 156); that the pteropod Limacina 

 retroversa (fig. 17), which, as a rule, is but sparsely represented in our tow nettings, 

 swarmed off Penobscot Bay on August 11 and 14, 1913 (stations 10091 and 10101); 

 that fragments of a siphonophore (Stephanomia) formed fully half the catch of the 

 40-meter haul off Cape Cod on July 8 of that same year (station 10058); and that the 

 ctenophore Pleurobrachia pileus often fills the water to the exclusion of almost every- 

 thing else in the neighborhood of German Bank (fig. 18). 



In summer and early autumn the large medusEe Cyanea, Aurelia, and Stauro- 

 phora often gather in vast numbers in narrow lanes or windrows, though usually for 

 brief periods (p. 362), and at this same season the hydroid medusa Phialidium lan- 

 guidum is often so abundant on the surface that it fills the tow net to the brim 

 (p. 350). Young fish, too, sometimes occur in numbers sufficient to loom large in the 

 total catch, notable instances of which have been the swarming of young silver hake 

 off Cape Cod, mentioned above (p. 18); likewise of young rosefish (Sebastes) near 

 Cape Elizabeth on July 19, 1912 (station 10019), when several hundreds were taken 

 (Bigelow, 1914, p. 101), off Massachusetts Bay on August, 9, 1913 (station 10087), 

 and near Cashes Ledge, September 1, 1915 (station 10308). Occasionally we have 

 encountered notable quantities of fish eggs, particularly of squirrel hake ( Urophycis 

 chuss), in Ipswich Bay, July 16, 1912 (station 10008); of silver hake (Merluccius) 

 near Monhegan Island and off Mount Desert, on August 4 and 18, 1915 (stations 

 10303 and 10305); of dinners (Tautogolabrus) at many localities along shore in sum- 

 mer, especially in Massachusetts Bay 7 (station 10340-10343); and of haddock over 

 their spawning grounds on Georges Bank during the early spring (fig. 19). 



In summer, generally speaking, copepods are relatively most abundant in the 

 western side of the gulf, less so in the eastern, the result being that, in spite of the 

 qualitative uniformity of the tow nettings from station to station, their general 

 aspect is usually most monotonous off the coasts of Massachusetts and southern 

 Maine and out thence to the western basin, and most diversified in the central parts 

 of the gulf and in its deep eastern trough. The only notable exception to the mid- 

 summer dominance of calanoids anywhere in the open gulf north of its offshore 

 banks (local swarmings of other animals, such as those just mentioned, seldom rival 

 the copepods in actual abundance, whether measured by bulk or by numbers) is the 

 Pleurobrachia swarm of the German Bank region, which I have already described 

 in the several preliminary reports on our cruises (Bigelow, 1914, 1915, and 1917). 

 Since we have found this ctenophore in abundance at that same general locality dur- 

 ing the successive Augusts of 1912, 1913, and 1914, and again on September 2, 1915, 

 this is evidently a regular phenomenon of summer. Having occasion to recur to it in 

 a later chapter (p. 365) , I need add here only that Pleurobrachia, large and small, 



7 The ledges oft Cohasset are a very productive nursery for this fish, judging from the quantities of its eggs that are to be found 

 there. 



