564 BULLETIN 159, UNITED STATES NATIONAL MUSEUM 



26. Distal segment of fifth legs longer than wide, armed with 5 



setae; inner expansion of basal segment much reduced, with 

 only 2 setae; bottom forms, fresh water. 



cf Attheyella Brady, 1880 (p. 233) 

 Distal segment of fifth legs wider than long, armed with 4 setae; 

 inner expansion of basal segment longer than distal segment, 

 with 3 setae; fresh water (Peruvian Andes). 



cf Qodetella Delachaux, 1918 



27. Rami of first legs equal in length; endopod of second antennae 



3-segmented, exopod 1-segmented; no rudiments of sixth 

 legs present in male; fresh water, subterranean. 



cf" ? Viguierella Maupas, 1906 

 Endopod of first legs shorter than exopod; endopod of second 

 antenna 2-segmented, exopod 1-segmented; rudiments of 

 sixth legs present in male; in meadow moss. 



cf 9 Phyllognathopus Mrdzek, 1894 

 Endopod of first legs longer than exopod; endopod and exopod 



of second antennae each made up of 2 segments 28 



28. Distal segment of fifth legs narrow-elongate, with 5 setae; inner 



expansion of basal segment well developed, with 6 or more 

 setae; fresh water, among plants- ? Canthocamptus Westwood, 1836 (p. 231) 

 Distal segment of fifth legs broadly oval, with 6 setae; inner 

 expansion of basal segment only moderately developed, with 

 4 setae or less; salt water, littoral 9 Pseudodiosaccus T. Scott, 1906 



29. Endopod of first legs made up of 3 segments 30 



Endopod of first legs made up of 2 segments 39 



Endopod of first legs 1-segmented, much reduced in size; exopod 



of second antennae lacking or replaced by a seta; second and 

 third endopods 1-segmented; on decaying algae. 



9 Eurycletodes G. O. Sars, 1909 

 Endopod of first legs lacking, replaced by a dagger-shaped 

 spine; of second and third legs 2-segmented; exopod of 

 second antenna 1-segmented, with 4 setae; on seaweed in 

 trawl net 9 Pseudocletodes T, Scott, 1893 



30. First antennae 5-segmented, distal segment much longer than 



the 2 preceding segments combined _ 31 



First antennae 6- to 10-segmented, distal segment much 



shorter than the 2 preceding segments combined 32 



31. Rostrum triangular, with apical filaments; caudal rami longer 



than wide, their lateral margins naked, or with a few scat- 

 tered hairs; shallow water (Norwegian coast). 



9 Cletomesochra G. O. Sars, 1920 

 Rostrum semielliptical, without filaments; caudal rami as wide 

 as long, both lateral margins densely fringed with coarse 

 hairs; shallow water (Scottish seas)-. 9 Heteropsyllus T. Scott, 1894 



32. Caudal rami long, narrow, and widely separated 33 



Caudal rami short, broad and close together 34 



33. Rami of first 4 pairs of legs slender, elongate; fifth legs enlarged 



into enormous laminae, 2-segmented in female; in male small 

 and 1-segmented; sandy bottom, 30 fathoms. 



cf 9 Pteropsyllus T. Scott, 1906 

 Rami of first 4 pairs of legs much widened, especially the basal 

 segments of endopods; fifth legs minute, 2-segmented, no 

 basal expansion; muddy bottom, 30-100 fathoms. 



9 Cervinia Norman, 1878 



