COPEPODS OF THE WOODS HOLE REGION 115 



Male. — Fifth segment smoothly rounded at the posterior corners; 

 grasping antenna considerably swollen ; second segment of right fifth 

 leg dilated through the center, with a prominent papilla, tipped with 

 a spine, on the inner margin; third segment slender, longer than 

 any of the others, with a sinuous inner margin ; end segment swollen 

 basally, slender distally, with three tiny inner spines; end segment 

 of left leg longer than penultimate segment, enlarged at the tip, with 

 a rounded process at each corner. Total length, 1.1-1.3 mm. 



Remarks. — The absence of processes at the corners of the fifth seg- 

 ment, the smooth dorsal surface of the anal segment and caudal 

 rami, and the relative proportions of the segments in the fifth legs 

 are the distinctive characters. Sars said of this species in Europe 

 that it was found only in fresh water, but here in the Woods Hole 

 area some of the ponds mentioned above are quite brackish. 



Genus EPISCHURA Forbes, 1882 



Head with a distinct cervical depression; fourth and fifth seg- 

 ments more or less completely f u^d, with rounded posterior corners ; 

 urosome 4-segmented in female, 5-segmented in male ; caudal rami each 

 with three large setae ; abdomen of male with prehensile appendages 

 and usually distorted to the right; endopods of first four pairs of 

 legs 1-segmented, exopods 3-segmented; fifth legs uniramose, 3-seg- 

 mented in female ; in male right fifth leg biramose, left uniramose. 



Remarhs. — Only one species has been found in the present area, 

 but further examination of the lakes and ponds will very likely re- 

 veal another species, and so the distinction between the two i,s here 

 given. 



KEY TO THE SPECIES 



FEMALES 



1. Abdomen distinctly flexed to riglit ; external seta of each caudal 



ramus much larger than other two lacustris 



Abdomen symmetrical, not flexed to right ; the 3 setae on each 

 caudal ramus all the same size nevadensis (p. 115) 



MALES 



1. First abdominal segment much longer than genital segment, 



with a long, straight, triangular process on right side lacustris 



First abdominal segment no longer than genital segment, its 

 process winglike, toothed on posterior margin and hooked at 

 tip nevadensis (p. 115) 



EPISCHURA NEVADENSIS Lilljeborg 



FiGUKE 77 



Episcliura nevadensis Lrtx-JEBOEG, Mem. Soc. Zool. France, vol. 2 , p. 145, 

 pi. 2, figs. 12, 24, pi. 3, fig. 21, 1889.— GiESBRECHT and Schmeil, Das Tier- 

 reich, Lief. 6, Copepoda, p. 99, 1898. 



Occurrence. — Both sexes found in abundance in a small lily pond 

 south of Ashumet Pond, Falmouth; Crockers Pond, Falmouth; 



