COPEPODS OF THE WOODS HOLE REGION 339 



tapered on either side to a bluntly rounded point. Total length, 

 1-2 mm. 



Male. — Body smaller and more slender than in the female ; cephalic 

 segment one-fourth longer than the rest of the metasome, second, 

 third, and fourth segments diminishing regularly in width, the 

 second only with projecting corners; urosome shorter and stouter 

 than in the female ; genital segment considerably dilated at its ante- 

 rior margin ; caudal rami shorter and without the serrate spines on 

 their outer margins. First antennae twice geniculate, reaching the 

 fourth metasome segment when straightened and reflexed, the mid- 

 dle section scarcely swollen at all, the terminal section quite short; 

 rudimentary sixth legs at posterior corners of genital segment, each 

 with three plumose setae. Total length, 0.75-0.9 mm. 



Remarks. — This is a very cosmopolitan species and is found at 

 the margin of the largest lakes as well as in ditches and small pools. 

 It is a true bottom form and moves about with restless energy and 

 considerable speed. It is almost never captured in surface tows or 

 in company with those species that are designated as limnetic. It 

 is also strictly a fresh-water copepod and is averse to even the 

 slightest degrees of salinity. 



EUCYCLOPS PRASINUS (Fischer) 



Figure 202 



Cyclops prasinus FiscHESt, Abh. math.-phys. Classe kon. Akad. Wiss., Munich, 

 vol. 8, p. 1652, pL 20, figs. 19-26a, I860.— MabsbI, Trans. Wisconsin Acad. 

 Sci., vol. 16, pt. 2, no. 3, p. 1097, pi. 79, figs. 1, 2, 3, 10, 1910. 



Occurrence. — ^A limited number of both sexes was obtained from a 

 small pond near the outlet of John Pond, Mashpee, from Great Pond, 

 Barnstable, and from a small pond near Edgartown on Marthas 

 Vineyard. 



Color. — Body transparent, with a brownish tinge, especially upon 

 the dorsal surface; a narrow band of reddish brown across the 

 posterior margin of the cephalothorax ; second metasome segment 

 much lighter than the following segments; no eye visible; urosome 

 bluish ; younger specimens nearly white. Herrick said that the color 

 varied from deep indigo blue to greenish brown, and Forbes found 

 both blue and pink sf)ecimens, so that the color is not at all constant. 

 The prevailing color of European specimens is green. 



DistHhution. — Azores (Eichard) ; Ceylon (Daday) ; Calcutta 

 (Gurney) ; Germany (Vosseler) ; France (Richard) ; British Isles 

 (Brady, Scourfield) ; Switzerland (Graeter) ; Great Lakes (Marsh) ; 

 Minnesota (Herrick) ; Massachusetts (Cragin, Forbes) ; Wisconsin 

 (Marsh) ; Nebraska (Brewer) ; Indiana (Juday) ; Mississippi Valley, 

 Florida (Forbes), 



