PLANKTON OF THE GULF OF MAINE 



445 



visible with the naked eye" (Bigelow, 1914a, p. 415). Curiously enough, this species 

 has not been detected in our tows over the offshore slope of the bank in summer, 

 though represented there in March, 1920 (station 200(39). 



Portland 







CV 



■-- 





»r«^" 



im , «r»K*SK2 



W 



PlO. 128.— Locality records for Rhi:osolenia sctigera (©) and Rh. tlylifarmis (O) 



The comparative scarcity of Rh. styliformis in the inner parts of the Gulf of 

 Maine, contrasted with its abundance over large areas of the open north Atlantic 

 in summer (Cleve, 1897; Ostenfeld, 1913), suggests that the optimum salinity for 



