418 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 3S. 



all the segments minutely crenulated. Caudal rami unusually pro- 

 duced, about three times as long as broad. 



Occurrence. — Found, in a surface 

 tow made by Mr. Yinal X. Edwards 

 of the r. S. Fish Commission at 

 Woods Hole, December. 



Distribution. - - Norwegian coast 

 (Sars); Franz Josef Land (Scott). 



This species appears heretofore not 

 to have been reported from Ameri- 

 can shores. Seemingly a boreal form, 

 broughl to the Woods Hole region 

 by the Labrador current. 



Fl<;. 10. — THALESTBIS GIBBA. a, FIFTH FOOT OF 

 FEMALE I \l"Ii B SABS); b, FIFTH FOOT OF MALE. 



Genus HALITHALESTRIS Sars, 190S. 



HALITHALESTRIS CRONI (Kroyer). 



Harpacticus croni Kroi er, Gaimard's Voyage en Scandinavio, 1S45, Znol., pi. 43, 



figs. 3, a-n. 

 Thalestris serrula to Bkady, Copepoda of the British Islands, vol. 2. 1880, p. 133, 



figs. 2 1 1 (male . 

 Halithalestris croni G. 0. Sars, Crustacea of Norway, vol. 5, L903, p. 118, pi. 72, 



L2 figs. 



Length. — Female, 2.3 mm.; male, 1.7 mm. 



Characters. Cephalic segment hardly longer than the three follow- 

 ingsegments taken together. Rostrum short. Genital segment about 

 a^ long as wide. Furca very long, about half as long as the abdomen 

 and with widely divergent rami. First an- 

 tennae shorter than the cephalic segment. 

 Fifth leg reaching nearly to the middle of 

 the genital segment, its terminal segment 

 (female) oval, and with six marginal bristles, 

 of which two are rather long. The same 

 segment of male more elongate (fig. 1 \l>). and 

 terminal seta the longer. Basal segment 

 triangular, with live terminal seta' in female 

 and three in male, the middle one in each case 



being the longer. Egg sacs very large,reach- 

 ing about to middle of furcal rami. 



Body of a lighl greenish hue, and com- 

 monly filled with clear oil bubbles of various 

 size--. 



Iianaiks. Our of the largest known Harp acticoids, and also very 

 unusual in its habits in that it leads a truly pelagiclife. Williams 

 (1906) speaks of collecting it by scraping piles at high tide at Rocky 

 Point in Narrafansett Bay. He calls his specimen Thalestris 

 serrulata Brady, which is mentioned above as a synonym, but as 

 Halithalestris croni seems to be truly pelagic, and such a habitat as 



Fig. LI. Halithalestris croni. 



(7, FIFTH FOOTOFFEM M I I \FTER 

 S IRS i; b, FIFTH FOOT OF HALE. 



