128 Illinois State Lahoratori/ of Natnr<(l Ilistorii. 



its longer antennae, its smaller size, and by characters derived 

 from the right antenna and the fifth foot of the male. The 

 thorax is symmetrically elliptical in shape, broadest at the 

 middle. The posterior angles are not produced or 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 

 abdomen itself is very short, its length contained about tln-ee 

 and one third times in that of the cephalothorax. The 

 antenna of the female is long and slender, 25-jointed, reach- 

 mg a little beyond the tip of the abdomen. 



" The fifth pair of legs in this sex is similar to those of D. 

 shoshone, but much smaller. The inner ramus is not jointed. 

 It is longer than the basal joint of the outer ramus, bears 

 two stout plumose setae at its tip, somewhat shorter than the 

 ramus itself, and has likewise at its inner tip a patch of small 

 spines or fine hairs. The second segment of the outer ramus 

 with its terminal claw is two thirds as long again as the pre- 

 ceding segment, the breadth of the latter two thirds its length. 

 The third joint is indicated by a single long stout seta and 

 one or two smaller ones. 



"In the male the geniculate antenna is relatively rather 

 slender, its last two joints without special appendages, its 

 penultimate with a slender transparent apical process, reach- 

 ing about to the middle of the succeeding segment, acute at 

 tip, but neither serrate nor emarginate. Fifth pair of 

 legs in the male [PI. XXVII., Fig. 1] usually without inter- 

 nal ramus to the right leg, but this ramus sometimes repre- 

 sented by a small rudiment. The limb is usually slender 

 and its terminal claw short. The basal segment of the outer 

 ramus is nearly as long as the adjacent segment of the 

 pedicel, and the slender second segment of this ramus is 

 fully as long. Long lateral spine borne near the tip of this 

 segment. The terminal claw is about two thirds as long as 

 the segment, is somewhat abruptly angulated near its base 

 and slightly recurved at the tip. The inner ramus of the left 

 leg is very stout and long, reaching almost to the tip of the 

 outer ramus, is slightly curved outwards and has the apex 



