188 BULLETIN OF THE BUREAU OF FISHERIES 



Brady, as he himself admitted in his later writings, confused the two genera, Artotragus and Astero- 

 cheres, and should have assigned his species to the latter instead of the former. Most of the species 

 of this genus are parasitic upon, or commensal with, some invertebrate animal, but Brady gave no 

 information upon this point. Scott, in his "Catalogue of the Crustacea of the River Forth," 

 reported obtaining this species in the water passages of sponges (Chalina oculala) growing on the 

 walls of a pier. It was later recorded by Norman and Brady from a tidal pool on the coast of 

 England, and it was added that this was probably a truly commensal or parasitic species, acci- 

 dentally found in a free condition. This readily explains why more specimens were not found in 

 the present collections, and it is significant that these two came from close to the coast of Maine 

 south of Portland [station 20059]. 



Calanus finmarchicus (Gunnerus) 9S 



General distribution. — Farran (1910, p. 83), whose words I can not better, 

 has described the distribution of Calanus finmarchicus as " centered in the North 

 Atlantic. It has also been recorded from the South Atlantic off Cape Colony, the 

 west coast of South and North America, 96 the Mediterranean, the Adriatic, and the 

 Polar Ocean." Following the North Atlantic around from east to west, we find 

 it occurring in dense though limited swarms off the mouth of the English Channel 

 (Farran, 1910) ; on the south and west coasts of Ireland, where Farran (1903) found 

 it the most abundant and economically important of the copepods; and on the west 

 coast of Scotland (T. Scott, % 1898, p. 182). Many authors have described the ex- 

 traordinary abundance of this species in Norwegian seas. Gran (1902), Paidsen 

 (1906), and Damas (1905), in particular comment on the shoals of it between Nor- 

 way, Iceland, and Greenland. The Ingolf expedition (With, 1915) had it at many 

 localities off west and east Greenland. Sars (1900, p. 35) describes it as "by far the 

 commonest of all the Copepoda in the north polar basin explored by the Fram 

 expedition, forming, indeed, in all the samples the great bulk of the contents." 

 Cleve (1900) remarked its abundance in the Labrador current. Herdman, Thomp- 

 son, and Scott (1898) record it from practically every tow netting across the North 

 Atlantic from Liverpool to the Straits of Belle Isle — largest in the Labrador current — 

 and Farran (1910, p. 83) speaks of it as "in great abundance along the coast of North 

 America in the path of the Labrador current, forming, in the summer months, a 

 rich belt, which, off Newfoundland, is at least 500 miles wide." Corroborating this, 

 the international ice patrol has taken great masses of it on the Grand Banks; Willey 

 (1919) found it the commonest copepod between Nova Scotia and the Newfoundland 

 Banks, in the Gulf of St. Lawrence, and along the outer coast of Nova Scotia. 



It dominates the plankton of the Gulf of Maine at all seasons, as will shortly 

 be described, and outside the immediate coastal zone is usually plentiful and often 

 the dominant copepod over the continental shelf off southern New England to longi- 

 tude about 72° W. ; that is, abreast of Long Island, New York (Bigelow, 1915). South 

 of this its occurrence along the seaboard of the United States becomes more seasonal 

 and less regular. It is to be expected in abundance over the shelf between the 

 latitudes of New York and Chesapeake Bay during the cold half of the year and into 

 early summer, Rathbun (1889) having found it characterizing the plankton at many 



'» According to With (1915) the relationship of C. helgolandicus Sars to C. finmarchicus is still in doubt, but Dr. C. B. Wilson 

 writes " Whatever may be the outcome, it£eems reasonably certain that all the specimens from the Gulf of Maine are finmarchicus." 

 K Esterly (1905, p. 126) describes it as the commonest copepod about San Diego, Calif., and as often very predominant. 



