PECULIAR HABITAT OF A PYCNOGONID (ENDEIS 



SPINOSUS) NEW TO NORTH AMERICA, WITH 



OBSERVATIONS ON THE HEART AND 



CIRCULATION.' 



LEON J. COLE. 



During the summers of 1904, 1905 and 1906, sargasso, or 

 gulf-weed, at various times drifted into Vineyard Sound in con- 

 siderable abundance. This is the case some years, while others 

 it may seldom be seen or may be wholly absent during the entire 

 season. Gulf -weed is borne northward each season in large 

 quantities by the Gulf Stream, which here lies nearly a hundred 

 miles off the coast, and its appearance in these in-shore waters 

 would seem to depend in large part upon the occurrence and 

 prevalence of southerly and easterly winds, which divert a cer- 

 tain amount of it shoreward from its course further out. In 

 1904, and presumably also in the two succeeding seasons, al- 

 though my records do not state specifically as to this, the weed 

 was covered with a delicate but very abundant growth of the 

 hydroid Obelia dichotoma (Linn.).^ Living among the colonies of 

 this hydroid, and clinging tenaciously to its stems and branches, 

 occurred a slender pycnogonid, a species of Endeis, both adult 

 males (many of them carrying eggs) and adult females, as well as 

 young in various stages of growth, being found in great numbers. 



The largest of these pycnogonids were of a considerable size, 

 being approximately 15 mm. across from tip to tip of the extended 

 legs; but all were nearly white, or of a light straw color, in gen- 

 eral appearance, which rendered them far from conspicuous 

 among the similarly colored hydroid stems. Examined individu- 

 ally, with more care, it was found that the intestine and its 

 diverticula in the legs usually appeared greenish, probably due 

 to its contents, while there was a pinkish tinge at each of the 

 articulations of the different joints (articles) of the legs. When 



' The observations reported in this paper were made in the laboratory of the 

 United States Bureau of Fisheries at Woods Hole, Mass. 



^ The identification of this species was kindly confirmed for me by Professor 

 C. W. Hargitt. 



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