PLANKTON OF THE GULF OF MAINE 



379 



The obvious inference from this is that there is a winter maximum and spring 

 minimum for Stephanomia in the Gulf of Maine. Other years might yield quite 

 different results, however, and it is questionable whether the concentration of 

 Stephanomia in the southwestern part of the gulf, suggested by the chart (fig. 103), 

 and its apparent rarity in the southeastern part- and on Georges Bank, are any- 

 thing more than accidental, especially when we remember that the neighborhood 

 of Grand Manan is the only locality in the gulf where it has ever been found of 

 large size (Fewkes, 1SS8). 



Alexander Agassiz's (1865) discovery of very young stages of this species in 

 Massachusetts Bay in early summer is undeniable evidence that it breeds in the 

 gulf, but how regularly it does so from year to year, what proportion of the local 

 stock results from local reproduction and what from immigration, and what rela- 

 tionship the fluctuations in the local stock of Stephanomia bear to hydrographic 

 conditions are questions for the future. 



DIphyes arctica Chun 



The faunal status of this species is discussed in an earlier chapter (p. 64). The 

 Gulf of Maine records are as follows: Southeast slope of Georges Bank, July 22, 

 1914 (station 10220); outside the continental edge off Shelburne, Nova Scotia, 

 June 24, 1915 (station 10295), and March 19, 1920 (station 20077); near Lurcher 

 Shoal and in the Eastern Channel, April 12 and 16, 1920 (stations 20101 and 20107). 



Other siphonophores 



The occurrence of Physophora and Physalia is discussed above (p. 55). To 

 complete the record of the group in the Gulf of Maine I have only to mention a 

 single Diphyes trvncata 19 from the northeast slope of Georges Bank, July 22, 1914 

 (station 10220), a few more examples of this species from our deep stations off its 

 southwest face in February and May, 1920 (stations 20044 and 20129), and two 

 taken in the northeastern basin of the gulf off Grand Manan on April 12 of that 

 same year (station 20101). The beautiful Agalma elegaivs, so common in the inner 

 edge of the Gulf Stream and which sometimes even reaches the coast west of Cape 

 Cod (Fewkes, 18S1), has never been taken within the Gulf of Maine. 20 



Pelagic hydroids 



In an earlier chapter (p. 33) the floating hydroids that we have encountered 

 over Georges Bank are mentioned. The records on which this observation is based 

 are as follows: 



On April 14, 26, and 27, 1913, campanularian hydroids were found floating on the 

 top of the water over the bank (Bigelow, 1914a, p. 414; lat. 41° 37' N., long. 67° 

 18' W., and about lat. 41° 40' long. 68° 30'), some of the specimens being complete — 

 that is, with all the ends of the stems rounded, closed, and apparently growing, as 

 Dr. S. F. Clarke reported on examining them. On the 9th of the following July 



'• For a discussion of this species see Bigelow, 1913, p. 73; 1918, p. 422; and Moscr, 1913, p. 232. 



" Agalmid fragments taken during the summer cruise of the Grampus in 1912 were provisionally referred to this species, but 

 subsequent study leads me to believe that they were in reality the common Stephanomia cara (p. 378) 



