North American Centropagidce. 265 



ashlandi Marsh, D. pallidus Herrick, or D. siciloides, I), on 

 gonensis, and 1>. nlinutus, Lilljeborg, and sometimes with two 

 or more of these species. It has been found in Illinois, 

 Indiana, Ohio, Minnesota, Michigan, Wisconsin, and also at 

 East Portland, Oregon. 



DOUBTFUL SPECIES. 



Epischura fluviatilis Heerick. 



Epischurafluviatilis, Herrick, '83a, p. 381. PI. V.. Fig. 10-20. 

 Epischura fluviatilis, Herrick, "84, p. 133. PI. Q, Fig. 14-16. 

 Epischurafluviatilis, Herrick, '87, p. 13, PI. II., Fig. 21-24. 

 Epischurafluviatilis, de Guerne et Richard, ? 89b, p. 92, PI. IV., Fig. 



13. 20. 

 Epischurafluviatilis, Forbes. "93. p. 254 (foot-note). 

 Epischurafluviatilis,. Herrick and Turner, '95, p. 83, PI. XIII., Fig. 



14-16. 

 Lamellipodia [Epischura] fluviatilis. Sehrneil, "98, p. 183. 



Of small size, body rather slender ; color greenish- blue. 

 Cephalothorax imperfectly six-segmented. Abdomen three- 

 segmented, differing in no way from that of Diaptomus except 

 in the number of f ureal seta?. In the male the second abdom- 

 inal segment bears on its left side a peculiar process con- 

 sisting of two parts forming a clasping organ, the inner part 

 of which is about as long as the third segment and armed at 

 the apex with two small spines, the outer part being slender, 

 curved, and about twice as long as the inner. 



Antennae 25-segmented, extending somewhat beyond the 

 end of the thorax. Eight male antenna geniculate between 

 the 18 and 19th segments; last six segments not ankylosed, 

 enlarged portion not greatly swollen. 



Swimming legs biramose, the outer ramus consisting of 

 three segments, the inner ramus of one segment. Basal seg- 

 ments of the two legs fused beyond the last. 



Fifth pair of legs of male uniramose, the two basal seg- 

 ments entirely fused. Eight fifth leg three-segmented, the 

 first two segments subquadrate and subequal, about three 

 times as long as wide and entirely unarmed. Third segment 

 slightly longer and broader than the second, tapering to a 



