PLANKTON OF THE GULF OF MAINE 



283 



have been uniformly distributed vertically, the numbers present per cubic meter 

 of water work out as follows for our richest catches of the species: 



Rhincalanus comutus Dana 



This'species has its center of distribution in the Tropic belts of the three great 

 oceans. It has been described from the Sulu Archipelago, from the Philippines 

 (Brady, 18S3), and from the western Pacific between latitudes 7° S. and 15° N. 

 (Giesbrecht, 1892). It is common in the Malay Archipelago (Cleve, 1901 ; A. Scott, 

 1909). Thompson and Scott (1903) had it at ten stations in the Indian Ocean; 

 A. Scott (1902) reports it from the Red Sea; but up to the present I have found 

 no record of it in the Mediterranean. The German South Polar expedition found it 

 widespread in the South Atlantic (Wolfenden, 1911). To the northward it is reported 

 from the equatorial belt off Africa; from the Gulf of Guinea, where T. Scott (1894) 

 found it one of the most common and widely distributed species; and in the eastern 

 side of the Atlantic at a few stations up to latitude 52° (Thompson, 1903). The 

 only previous report of it on the American side is from one station outside the con- 

 tinental edge off Cape Sable by the Canadian fisheries expedition, July, 1915 (Willey, 

 1919). So far as eastern North American waters are concerned, the true home of 

 this species lies well outside the continental edge, in almost Tropic temperatures and 

 high salinities. 



In the Gulf of Maine this species is an accidental stray, appearing in the lists 

 for nine hauls, including both horizontals and verticals (fig. 72; tables, p. 298-305), 

 the captures within the gulf being in the northeastern part of the basin, off Penobscot 

 Bay, off Cape Elizabeth, off the Merrimac River, and in Massachusetts Bay, a 

 localization along the northern and western shores which parallels the distribution of 

 other immigrants. There are also two station records for it on the continental 

 shelf off Marthas Vineyard. 



Two of the records for R. cornutiis in the inner part of the gulf are for March, 

 two for September, and three for December. Evidently it may enter at any time of 

 year, and is about as apt to do so at one season as another. The records off Marthas 

 Vineyard were for October 21 and 22, 1915 (table, p. 298). 



There is no reason to suppose that this copepod is able to breed successfully 

 within the gulf or to establish a permanent foothold there, the records from within 

 the gulf all being for scattering specimens, up to a frequency of about 455 per square 

 meter off Massachusetts Bay, September 29, 1915 (station 10321), at most 2 per 

 cent of the copepods. Off Marthas Vineyard, however, the vertical haul yielded 

 about 2,000 per square meter at one station (10333). 



