182 BULLETIN 15 8, UNITED STATES NATIONAL MUSEUM 



KBTSr TO THE SPEX^IES 



FEMALES 



1. Basal segment of first endopod shorter than basal segment of 



exopod ; distal segment of fifth legs twice as long as wide 2 



Basal segment of first endopod as long as basal segment of 

 exopod or longer ; distal segment of fifth legs only one-half 

 longer than wide 3 



2. Hand of maxilliped chela twice as long as wide, with a large 



spiniform process on its palmar margin at distal end tenellus (p. 182) 



Hand of maxilliped chela little longer than wide, without a 



spiniform process gracilis (p. 183) 



8. Body strongly compressed, more than four times as long as wide ; 

 inner expansion of basal segment of fifth legs with 3 



setae chelifer (p. 185) 



Body somewhat depressed, less than three times as long as wide ; 

 inner expansion of basal segment of fifth legs with 4 

 setae uniremis (p. 186) 



MALES 



1. Exopod of third legs much enlarged and considerably longer than 



endopod, with elongated, coarse spines 2 



Exopod of third legs little enlarged, and no longer than endopod, 

 with relatively short, slender spines 3 



2. Body strongly compressed, fourth segment scarcely wider than 



fifth, with inconspicuous epimeral plates chelifer (p. 185) 



Body somewhat depressed, fourth segment one-half wider than 



fifth, with prominent pointed epimeral plates uniremis (p. 186) 



3. Basal segment of second endopod four times as long as wide; 



hand of maxilliped chela with a spiniform process tenellus (p. 182) 



Basal segment of second endopod twice as long as wide ; hand of 

 maxilliped chela without a process gracilis (p. 183) 



HAEPACTICUS TENELLUS G. O. Sars 



Figure 123 

 Harpacticus tenellus Saes, Crustacea of Norway, vol. 7, p. 49, pi. 30, 1920. 



Occurrence. — Twenty males and females found among algae in 

 the Eel Pond at Woods Hole, June, 1925 ; three females from among 

 algae in Katama Bay, Marthas Vineyard, July, 1925. 



Distribution. — Norwegian coast (Sars). 



Color. — Body quite transparent, of a uniform whitish gray, 

 slightly washed with olive-brown along the grooves between the seg- 

 ments, but without definite pigment markings ; eye dark ruby red. 



Female. — Body somewhat depressed, the epimeral plates of the 

 metasome segments very inconspicuous ; fifth segment nearly as wide 

 as the fourth; urosome segments with smooth posterior margins; 

 caudal rami quadrangular, wider than long. First antennae 9-seg- 

 mented, the terminal portion (five distal segments) scarcely longer 

 than the fourth segment; hand of maxilliped chela twice as long as 

 wide, with a large spiniform process on its inner margin near the 



