442 Wisconsin Academy of Sciences^ Arts, and Letters. 



Ill the male fifth feet, the spines of the first basal segments 

 are prominent and acute. The second basal segment of the 

 right foot is twice as long as broad. The lateral hair is situat- 

 ed at the beginning of the distal third. The first segment of 

 the exopodite is quadrate, and bears a hyaline process on the 

 inner distal angle. The second segment is strongly curved and 

 equals in length the first basal segment. The lateral spine is 

 straight and rather small and situated just distad of the mid- 

 dle. The terminal hook is slender, slightly curved, and equal 

 in length to the rest of the foot v/ith the exception of the first 

 basal segment. It is denticulate on the inner margin. The 

 endopodite is small, much less in length than the first segment 

 of the exopodite. It is ordinarily pointed, but in some cases 

 the tip is rounded. The left foot reaches to the end of the 

 first segment of the right exopodite. The second basal seg- 

 ment is as long as wide, and strongly convex on the inner mar- 

 gin. The lateral hair is situated near the distal end. The 

 first segment of the exopodite is much longer than wide 

 and setose on the inner margin. The second segment is about 

 one-half the length of the first, and the inner surface is a con- 

 vex setose pad. The segment is terminated with two digiti- 

 form processes, of which the outer is the longer. The endopo- 

 dite is long and slender, reaching to the middle of the second 

 segment of the exopodite. It is either one-segmented or in- 

 distinctly two-segmented. The tip is distinctly setose. 



Length, accordng to Poppe: female, 1 mm.; male, 1.5 mm. 



Length, according to Lilljeborg: female, 1.9 mm.; male, 1.8 

 mm. 



My specimens averaged: female, 1.258 mm.; male, 1.15 mm. 



The original description by Poppe was from material col- 

 lected at Summit lake in the Rocky mountains, at a height of 

 5300 feet)- Lilljeborg's material was from Centerville, near 

 Fresno, California. 



The material from which my drawings were made was col- 

 lected by the U. S. Fish Commission in Alturas lake, Idaho. 

 Probably, then, it is widely distributed in the mountain re- 

 gion of the West. 



