CRUSTACEANS FROM WESTERN ATLANTIC TATTERSALl. 



17 



Genus EUPHAUSIA Dana 



19. EUPHAUSIA KROHMI (Brandt) 



Occurrence. — Station 10158, 600-0 m., 2,000 specimens; station 

 10160, 100-0 m., many. 



RemarTcs. — The distribution of this species in the area explored 

 by the Bache is interesting. It occurred in the same two hauls as 

 Meganyctiphanes norvegica and in no others, being replaced in the 

 purely oceanic waters by the closely allied species E. americana. 

 The enormous abundance of E. Jcrohnii at these two stations coupled 

 with its complete absence in all the other points suggests that possibly 

 it, like M. norvegica, should be regarded as a coastal and slope form 

 rather than as an oceanic species. This, however, is not in agree- 

 ment with previous records, for the species has frequently been 

 recorded from waters which are purely oceanic. Many of Hansen's 

 records (1915) from the west Atlantic off the American coast are 

 from the oceanic water outside the continental shelf. Perhaps 

 the true explanation is that E. Jcrohnii is not so much a coastal and 

 slope form as a boreal species representing a northern element in the 

 plankton off the American coast. Its wide distribution in the north- 

 ern parts of the North Atlantic from America to the European 

 Atlantic slope off Norway and the British Isles supports this view. 

 Its main distribution is, in fact, very similar to that of M. noi'vegica 

 but the latter extends much nearer into the coastal waters on both 

 sides of the Atlantic. 



20. EUPHAUSIA AMERICANA Hansen 



Occurrence 



