PLANKTON OF THE GULP OF MAINE 227 



In the Pacific it has been described from north of Papua, the Philippines, Straits 

 of Sunda, the China Sea, north of the Hawaiian Islands, and other localities between 

 latitudes 32° S. and 30° 22' N. (see Giesbrecht, 1892, and Brady, 1883, for lists of 

 Pacific records), but it does not appear in Esterly's (1905 and 1911) lists of the 

 copepods of the San Diego region. 



The geographic distribution of this species is thus tropical and warm tempe- 

 rate. The only previous records of Dwightia gracilis off the North American coast 

 are from the "Gulf Stream," 70 miles south of Marthas Vineyard, where many 

 were taken on July 25, 1899 (Wheeler, 1901, p. 188), and Woods Hole (Fish, 1925). 

 Dr. C. B. Wilson's lists add seven records for the Gulf of Maine (table, p. 297) and 

 one near Shelburne, Nova Scotia (station 10291). In the gulf, D. gracilis is to be 

 regarded as an immigrant of southern-oceanic affinity, and, correspondingly, most 

 of the locality records for it, like those for the two species of Rhincalanus and for 

 Scolecithricella, are in the peripheral belt near the eastern, northern, and western 

 shores. Being for the months of March, April, June, October, and December, they 

 show that it is to be expected in the gulf at any time of the year; but since all five 

 of the records from within the gulf have been based on odd specimens (three at sta- 

 tion 20063 were the most specimens noted in any one haul inside of Georges Bank), 

 either the immigrations into the gulf are in very small numbers and at rare inter- 

 vals or such as do enter survive only for a brief period in the low temperatures to 

 which they are subjected there. A somewhat larger catch (about 140 per square 

 meter) was made on the southeastern part of Georges Bank on March 12, 1920 (sta- 

 tion 20063) . It may be taken as certain that this copepod appears in the gulf only 

 as an immigrant, never breeding there. 



In tropical seas this species has been taken repeatedly on or close to the surface, 

 and the Gulf Stream specimens described by Wheeler (1901) were also, presumably, 

 from the surface; but it has not been found in any surface haul in the Gulf of Maine, 

 all the records there being from open-net hauls, vertical and horizontal, from depths 

 ranging from 30-0 to 190-0 meters. Apparently it is more apt to enter the gulf 

 at least some few meters down and to remain there as long as it survives in its jour- 

 neyings in the gulf. But for it, as for Scolecithricella (p. 285) and for the two species 

 of Rhincalanus (p. 283), the preponderance of captures near the coast of the gulf 

 points to the upper 50 to 100 meters, where the counterclockwise Gulf of Maine eddy 

 is most active, as the stratum in which it chiefly drifts. The chart for Rhincalanus, 

 Scolecithricella, and Dwightia (fig. 72) is a graphic illustration of the tendency of 

 natural flotsam of any kind, entering the eastern side of the gulf from the oceanic 

 basin offshore, above, say, 100 meters, and keeping at or above that level, to circle 

 its periphery, leaving its central basin bare. 



Ectinosonia neglectum G. O. Sars 



Thisharpacticoid is described by Sars (1903-1911) as abundant along the southern 

 and western coasts of Norway, usually in 10 to 20 fathoms on muddy bottom. He 

 also records it from polar islands north of Grinnell Land, and Willey (1920) men- 

 tions it from the Arctic coast of Canada. Apparently it is strictly a boreal-Arctic 

 species. I find no previous record of it on the east coast of North America, but 



