142 



BULLETIN OF THE BUEEAU OF FISHERIES 



northern sources, either around Cape Sable or from the mixed water along the outer 

 part of the continental shelf, for the maintenance of its numbers within the gulf. 



Fig. 51. — Occurrence of the euphausiid shrimps Nematoscelis megalops and Thysanoessa gregaria. #, locality records for 

 Nematoscelis, July to September, including Hansen's (1915); A, locality records for Nematoscelis, February to May, 

 1920; X, locality records for Thysanoessa gregaria 



Thysanoessa gregaria, G. O. Sars 



The fact that Thysanoessa gregaria occurs side by side with its boreal-Arctic 

 relatives Th. inermis, Th. longicaudata, and Th. raschii in the Gulf of Maine is, 

 as Doctor Tattersall writes me, an interesting phenomenon; for, unlike them, it is a 



