252 Illinois State Laboratory of Natural History. 



4 (3). First segment of right leg entirely unarmed. First 

 segment of left leg with comparatively slender process ; 

 second segment armed at the outer apical angle with a 

 small spine. lacustris. 



Epischura nordenskioldi Lilljeborg. 



Epischura nordenskioldi, de Guerne et Richard. 'e9b, p. 04, PI. I. 



Fig. 36; Pi. II., Fig. If), 23. 

 Epischura nordenskioldi, Herrick and Turner, '95, p. 85, Pi. XI.. Fig. 



2, 5, 9. 

 Epischura nordenskioldi. Schrneil. '9S. p. 183. 



About medium size, body rather robust, widest in front of 

 middle. Cephalothorax six-segmented, the first two segments 

 confluent and together somewhat longer than the remainder; 

 third segment slightly longer than either of the last three, 

 which are subequal ; last two segments distinct, the last 

 segment produced on each side at the posterior angle into 

 a bluntly-rounded lobe armed at the tip with a minute 

 spine. Abdomen (including furca) five-segmented, slender. 

 a little less than half as long as the cephalothorax ; first two 

 segments indistinctly confluent below ; third segment slightly 

 longer than the fourth. Furcal rami about twice as long as 

 broad and ciliate on the inner margin ; armed at the apex 

 with three slender plumose setae fully three times as long as 

 the ramus itself, at the outer apical angle with a short stout 

 spine, and on the dorsal surface, near the inner margin, with 

 a delicate smooth seta. Abdomen of male (furca included) 

 six-segmented, the second, third, and fifth segments armed on 

 the right side with prehensile processes ; flexed to the right but 

 slightly or not at all. First segment somewhat broader than 

 long, slightly produced along the left margin into a process 

 ending at the posterior angle in a lobe-like expansion. Sec- 

 ond segment slightly narrower and longer than the first ; pro- 

 duced on the right side in the form of a subtriangular plate, 

 somewhat longer than w 7 ide and pointing obliquely backward. 

 The process is armed at the tip with a small sharp spine, 

 on the inner margin, near the apex, with two or three rather 

 large teeth, and within these with a number of smaller 



