68 GEOL. AND NAT. HIST, SURVEY OF MINNESOTA. 



two strong spines. The first segment of the abdomen is much longer 

 than the entire remainder of the abdomen and bears a strong spine on 

 either side anteriorly. The stylets are short and ciliated internally. 

 The antennae reach to the end of the stylets. In the male the ante- 

 penultimate segment bears a straight process directed distad and but 

 slightly curved at the tip and shorter than the penultimate segment. 

 The thickened portion of the geniculate antenna is very much modi- 

 fied. The fifth foot of the female has an obscurely two-jointed inner 

 ramus much shorter than the first joint of the outer ramus. The 

 hook of the penultimate segment of the outer ramus is armed with a 

 short series of sharp spines along the middle third of the inner aspect 

 or rather nearer the base than the apex. There is a small spine at 

 the base of the terminal segment, which is distinct and carries two 

 long but unequal spines. The fiaal joint or claw of the outer branch 

 of right fifth foot of the male is very strong and gently curved, being 

 longer than the whole leg. The accessory spine is also heavy and 

 nearer the end than the base of the second segment, and is minutely 

 denticulate near its base. The inner ramus of the right foot is one- 

 jointed, very short, and slightly ciliate at the tip. The left leg 

 reaches to the tip of the inner ramus of the right leg. Its terminal 

 segment is of moderate size and ends in one immovable toothed spine 

 and a bristle; along its inner aspect a ciliated lamina is situated. The 

 preceding segment has a granular area along its inner aspect. The 

 inner ramus resembles that of the right leg. 



*Diaptoiims lintoni Forbes. 



Plate V, Fig. 12. 



Forbes '89. 



"A large red species occurring commonly with I), shoshone, but 

 distinguishable from it at a glance by its different shape, its longer 

 antenuie, its smaller size, and by characters derived from the right 

 antenna and fifth foot of the male. The thorax is symmetrically ellip- 

 tical in outline, broadest at the middle. The posterior angles are not 

 produced nor bifid, but are each armed with a minute spine. The 

 first segment of the abdomen of the female is not especially produced, 

 but bears at its broadest part a minute spine on each side. The abdo- 

 men itself is very short, its length contained about three and one third 

 times in that of the cephalothorax. The antenna of the female is long 

 and slender, 25-jointed, reaching a little beyond the tip of the abdo- 

 men. The fifth pair of legs in this sex is similar to those of D. sho- 

 shone, but much smaller. The inner ramus is not jointed. It is longer 

 than the basal joint of the outer ramus, bears two stout plumose sette 

 at the tip, somewhat shorter than the ramus itself, and has also at its 

 inner tip a patch of small spines or fine hairs. The second segment 



