COPEPODS OF THE WOODS HOLE REGION" 91 



the species sanguinexLS from Wellesley and Meclford, Mass, All these 

 species are here located definitely and quite abundantly in the Woods 

 Hole area, one or more of them being found in almost every fresh- 

 water pond examined. 



KEY TO THE SPECIES 

 FEMALES 



1. Endopods of fifth legs much shorter than basal segment of 



exopods, and without spines or setae minutus (p. 92) 



Endopods of fifth legs about as long as basal segment of 



exopods 2 



Endopods of fifth legs definitely longer than basal segment of 



exopods 3 



2. Seta on second basipod of fifth leg nearly as long as proximal 



exopod segment; second exopod segment dentate on inner 

 margin ; endopod setose at tip and armed there with 2 small 



spines sanguineus (p. 93) 



Seta on second basipod less than one-fourth as long as proximal 

 exopod segment ; second exopod segment smooth on inner 

 margin; endopod smooth at tip where it is armed with 2 

 plumose setae leptopus (p. 94) 



3. Inner margin of second segment of exopod of fifth leg smooth ; 



third segment represented by 3 spines, the inner one 



longest ■ spatulocrenatus (p. 97) 



Inner margin of second segment of exopod of fifth leg fringed 

 with setae or hairs ; third segment represented by 2 spines 

 only 4 



4. Spines on first basipod of fifth leg large, projecting beyond lateral 



margin; outer of the two spines representing third segment 



of exopod shorter than inner one birgei (p. 98) 



Spine on first basipod of fifth leg minute, not reaching lateral 

 margin ; outer of the two spines representing third segment 

 of exopod longer than iimer one oregonensis (p. 99) 



MALES 



1. Antepenultimate segment of right first antenna with a broad 



hyaline lamella extending beyond end of the segment; fifth 



endopods longer than first segment of exopod leptopus (p. 94) 



Antepenultimate segment. of right first antenna with a slender 

 process, longer than penultimate segment; no hyaline mem- 

 brane; right fifth endopod rudimentary and very short minutus (p. 92) 



Antepenultimate segment of right first antenna with a curved 

 process, shorter than penultimate segment; no hyaline mem- 

 brane 2 



Antepenultimate segment of right first antenna without either a 



membrane or a process 3 



2. Endopod of right fifth leg rudimentary and curved like a claw ; 



basal exopod segment three-fourths as long as second segment ; 

 left endopod nearly as long as exopod, 2-segmented, spatulate, 

 with crenate margin spatulocrenatus (p. 97) 



