342 BULLETIN" 15 8, UNITED STATES NATIONAL MUSEUM 



second antennae 4-segmented, without an exopod, the fourth segment 

 much shorter than the third. Outer exopod spines on first four legs 



3, 4, 4, 3 ; each fifth leg fused with the body segment and represented 

 by a plate armed with three setae, the outer one less densely plu- 

 mose than the other two. Semen receptacle occupying nearly the 

 whole width of the genital segment, anterior portion transversely 

 elliptical, posterior portion made up of two parts, each semilunar 

 and pointed distally. Total length, 0.9-1.26 mm. 



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

 relatively shorter; epimeral plates on second, third, and fourth seg- 

 ments pointed; urosome 5-segmented, the segments diminishing in 

 width posteriorly; caudal rami nearly as wide as long, the apical 

 setae jointed near their base, the inner one longer than the urosome. 

 First antennae 10- or 11-segmented, twice geniculate, the terminal 

 section made up of two segments; fifth leg like that of the female 

 but not so completely fused with the body segment; a sixth leg, 

 similar to the fifth, at each posterior corner of the genital segment. 

 Total length, 0.75-0.93 mm. 



Remarhs. — This species is world-wide in its distribution but not 

 abundant anywhere. Forbes said: 



The best character for the ready recognition of this species is its strong 

 superficial resemblance to the genus Canthocamptus. 



This, combined with the rudimentary form of the fifth legs, makes 

 it comparatively easy to identify. 



Genus PARACYCLOPS Claus, 1863 



Body stout ; metasome flattened, with lateral epimeral plates ; fifth 

 segment short, its lateral margins fringed with hair; urosome stout, 

 subcylindrical; genital segment a little wider than long; caudal rami 

 many times longer than wide, with dorsal spinules. First antennae 

 8-segmented and very short ; fourth segment of second antenna much 

 shorter than third. Outer exopod spines of first four pairs of legs 3, 



4, 4, 3 ; each fifth leg a 3-lobed lamella, with one apical and one outer 

 seta, and a long inner denticulated spine. A single species. 



PARACYCLOPS FIMBRIATUS (Fischer) 



Figure 204 



Cyclops fimbriatus Fischejr, Bull. Soc. Imp. Nat. Moscow, vol. 26, pt. 1, p. 94, 



pi. 3, figs. 19-28, 1853. 

 Platyci/clops fimhriatus Saks, Crustacea of Norway, vol. 6, p. 81, pi. 50, 1915. 

 Paracyclops flmbriatus Kiefer, Das Tierreich, Lief. 53, p. 41, 1929. 



Occwrrence. — Both sexes found in Gosnold Upper Pond on Cutty- 

 hunk Island and in the small pond on Rams Head Island in Hadley 

 Harbor. 



