134 BULLETIN OF THE BUREAU OF FISHERIES 



and Th. inermis), many large Meganyctiphanes, and a few Nematoscelis. Four days 

 later we again encountered a euphausiid plankton over the continental slope off 

 Shelburne, Nova Scotia (station 10233), where half-hour hauls on the surface, at 

 100-0 meters and at 200-0 meters, yielded, respectively, 125, 500, and 250 cubic 

 centimeters, chiefly euphausiids. On this occasion the surface catch consisted mainly 

 of Euphausia, but Nematoscehs dominated at 400 meters, with the two species 

 mingled at the 100-meter haul. An abundance of these two genera is perhaps 

 characteristic of this general location in summer, for we again found them in large 

 numbers over the continental slope nearby on June 24, 1915 (station 10295). This 

 does not apply to Browns Bank, however, which was barren of euphausiids on June 

 24, 1915 (station 10296), though productive of them the previous July; nor did we 

 find more than an odd specimen there in March or April, 1920 (stations 20072 and 

 20106). Small Th. longicaudata were numerous over the northeast part of Georges 

 Bank on March 13 of that year (station 20070). By April 16 (station 20108) they 

 had vanished thence, but the fact that we once more found small Th. longicaudata 

 very plentiful off the southwest face of the bank on May 17 (station 20129) sug- 

 gests that the swarm had drifted westward from one end of the bank to the other 

 during the interval from March to May. 



Turning now to the inner parts of the gulf, we have twice found the waters off 

 northern Cape Cod supporting larval and very young Thysanoessa in abundance 

 (July 8, 1913, station 10057, and August 28, 1914, station 10264). Medium-sized 

 and adult specimens of this genus (particularly Th. inernis, p. 135) were also taken in 

 large numbers in the eastern side of the basin in May (station 10270) and off Cape 

 Ann in August, 1915 (station 10306). On August 22, 1914 (station 10254), we found 

 Meganyctiphanes abundant in the deeper water layers of the western basin, but 

 the most interesting swarming of shrimps of this group in the western part of the 

 gulf was the sudden appearance of shoals of Thysanoessa raschii off the Isles of 

 Shoals late in April, 1913, as described below (p. 145). Provincetown Bay was 

 similarly invaded by "shrimps," very likely of this same species, in March, 1880, 

 as described by A. H. Clark (1887), and in August, 1923, euphausiids of some sort 

 were so plentiful at the surface off Penobscot Bay that Dr. George C. Shattuck 

 wrote me of seeing "a good many shrimp in the water" while sailing from Isle au 

 Haut to Matinicus Island during the last week of the month. 



All the congregations of pelagic shrimps mentioned so far have been sporadic, 

 or at least of brief duration; but euphausiids are often enough plentiful in the ex- 

 treme northeast corner of the deep basin, some 50 miles southwest of Grand Manan, 

 at various seasons, for this local abundance to be regarded as characteristic. Our 

 first visit to this locality (in August, 1912) did not suggest this (indeed, not a single 

 euphausiid was noted in the tow on that occasion), but many large specimens of 

 Meganyctiphanes norvegica were taken at this general location on August 13, 1913 

 (station 10097), in a haul from about 160-0 meters; again on August 13, 1914 (sta- 

 tion 10246, 150-0 meters); on May 10, 1915 (station 10273, 125-0 meters); on June 

 10, 1915 (station 10283, 100-0 meters) ; and in the basin, a few miles to the south- 

 ward, on August 7, 1915 (station 10304). If the year 1920 can be taken as typical, 

 this local abundance of Meganyctiphanes is as characteristic of spring as of midsum- 



