PLANKTON OF THE GULF OF MAINE 357 



most reasonable hypothesis is that the small form is evidence of conditions less 

 favorable, the larger specimens of an environment more favorable, for growth, though 

 both may mature their sexual products. 



ScYPHOMEDTJS/E 



Cyanea capillata var. arctica, Peron et Lesueur 



The distribution of the genus Cyanea, the largest of all the medusae, is very 

 wide along the coasts of both sides of the North Atlantic and Pacific Oceans and in 

 the Arctic Ocean. The genus is likewise represented in south Temperate and Ant- 

 arctic Seas, but not in the Tropics. Numerous supposedly distinct "species" of 

 Cyanea have been described, separated for the most part by color, size, and minor 

 anatomical differences, but these have been found to intergrade in so many cases 

 that, as I have remarked elsewhere (Bigelow, 1913, p. 92), it seems impossible to 

 distinguish more than one species of this genus in northern seas, where all its varieties 

 are connected by intermediates. Several of the latter, however, deserve recognition 

 in nomenclature, being not only well marked but occupying rather definite geographic 

 ranges. 



The Cyaneas which occur in the Arctic-boreal waters of the western side of the 

 North Atlantic province, from West Greenland to the region of Cape Cod and Nan- 

 tucket Shoals, are the largest of their race and usually of a rich brown and yellow 

 color. They form the basis of the "species" C. arctica of Peron et Lesueur and of 

 most recent authors. Following the coast west and south from Cape Cod we find 

 this northern form giving place to smaller, more yellowish Cyaneas (the var. fulva) 

 along southern New England and the Middle Atlantic States to the Carolinas, and 

 this form in turn to a still smaller and pinker race christened "versicolor" by L. 

 Agassiz, which is very plentiful locally from Cape Hatteras to the southern boundary 

 for the genus off Florida (Mayer, 1910, p. 600). 



Cyanea, like Aurelia (p. 362), is neritic and its life cycle is similar. The egg 96 

 develops to the planula stage among the folds of the mouth parts of its parent, and 

 when it is shaken free it attaches itself to the bottom, to develop there into the 

 tentaculate scyphostoma from which the young medusa? (ephyrae) are produced 

 serially by annular constrictions of the oral end. 



The distribution of this common red jellyfish in the Gulf of Maine is interesting 

 because its presence is a sure sign of coast or of banks water, and because it offers 

 a refuge to the fry of the haddock 97 . Locality records for it in the gulf are now very 

 numerous. In the neighborhood of Woods Hole (and probably this applies all 

 along the southern shores of New England) the young medusae of Cyanea appear 

 in March; by the end of the month "the calm surface of the water in Great Harbor 

 was literally spangled with the slightly protruding discs" (Bumpus, 1S98, p. 4S7); 

 by mid- April some have grown to a diameter of 7 inches (Mead, 1S98); many are 

 sexually mature at Woods Hole by May, though the youngest medusae (ephyra 

 stage) are still to be found there as late as the end of that month; and the mature 



•• On the development of Cyanea see L. Agassiz, 1862; Hyde, 1894; McMurrich, 1891; Hargitt, 1902. 

 " For an account of its movements in Norwegian waters see Damas (1909). 



