70 THOMAS SAY FOUNDATION 



the usual yellow ring capping the femora at the knees. 

 Wings subhyaline, with brown veins and a heavier infus- 

 cation upon the front of the cord and on the base of the 

 radial sector. There is occasionally an extra crossvein be- 

 tween veins R and M, forming a closed cell beyond the 

 cord. There is a heavy terminal branching of the radial 

 sector, with the branches all springing to rearward and 

 bending forward at their tips. 



Abdomen brownish, somewhat lighter toward the tip. 

 Tails yellowish brown, darkening toward the tip, much 

 exceeding the folded wing tips, their cylindric segments 

 clad with a short close pubescence. 



Male. Abdomen upcurving at the end and concave on 

 the dorsum of all the middle segments with lateral humps 

 or pads formed upon 5 or 6 to 8, these cushionlike pads 

 being oval or crescentic in form and covered with scurfy 

 pubescence. Segment 9 is strongly narrowed above, be- 

 ing broadly and deeply concave on the rear margin above, 

 and slightly produced to rearward beneath. The subgen- 

 ital scoop thus formed is not well marked off at its side, 

 but is crimped into a somewhat triangular gutter on the 

 mid-ventral apical margin. Segment 10 is cleft in two on 

 the dorsal side for the reception of the retractile U- 

 shaped supra-anal process, whose basal attachment forms 

 a triangular figure in brown at the base of the 10th ter- 

 gite, there strongly chitinized. The halves of the 10th 

 are again divided laterally by a deep notch, the rear 

 border of which is a linear flattened process that curves 

 forward and upward forming a genital hook, clad with 

 long hairs posteriorly and with short chitinous prickles on 

 its forwardly directed border. The retractile U-shaped 

 supra-anal process bears a sharply decurved thornlike 

 tip (PI. 4, fig. 4) and a pair of minute, club-shaped, 

 prickle-coated lateral stylets, and these are inclosed be- 

 tween two paragenital plates, from whose rear angles 

 above project two slender thorn-like processes. Subanal 

 plates small, obtuse-angled. 



Female. The subgenital plate is as broad as the ster- 

 num, generally well set off at its sides by a deep oblique 

 inwardly directed groove. Its apical margin overlaps 

 upon the base of segment 9, is very broadly rounded, and 

 deeply divided by a wide median notch. 



A wide-ranging northern species of great variability in 

 size and coloration, and even in genital characters, inter- 

 grading more or less completely with the two next follow- 

 ing. 



