420 THE CANADIAN ENTOMOLOGIST. 



Chcetotaxy. — Lateral verticals and two orbital bristles present. 

 Thorax. — Sutural ridge bare. 



Wings.— Angle formed by bend of fourth vein slightly more 

 acute than in male. 



Legs. — Vestiture throughout of short hair. Spine of posterior 

 trochanter distinct, anterior face of femur with but two rows of 

 bristles, an upper and lower, a few bristles proximally and 

 posteriorly on ventral face. Middle femur with "comb". 



Chcetotaxy. — Scutellarapicals absent; four sternopleurals; lower 

 sternopleurals fewer and anterior ones more distinctly bristly. 



Abdomen. — Oval; vestiture throughout of short reclinate 

 bristles. Posterior margins of ventral plates each with a row of 

 bristles. 



Genital Segments. — Protuberant. First segment consisting of 

 two lateral lips that converge dorsally meeting in a slight depres- 

 sion and ventrally are separated by fifth ventral plate which 

 they sometimes overlap, on dorsal half their edges with a row of 

 close set, strong bristles that converge backward and downward, 

 tips of uppermost usually crossing, each bears short hairs just in 

 front of posterior edge, spiracles slightly above centre. Spiracles 

 of fifth segment plainly visible. 



Described from 13 & and 13 9 specimens. About 500 

 examined. 



Range. — Collected at Laurel and in the Bridger Mountains, 

 Montana. 



The colour of the parafrontals and genae is usually faintly 

 aurichalceous, sometimes silvery gray, the deeper reflections when 

 viewed from the side vary from brown to deep gray. In a single 

 male specimen the lateral vertical bristles were weakly developed. 

 The abdomen of d 71 often appears more oval than conical, but the 

 latter is more typical. Ordinarily the vestiture of the second 

 ventral plate is decumbent like that of the third, but occasionally 

 may be a little more erect. As seen when the abdominal segments 

 are in their normal position the sides of the second and third 

 ventral plates appear almost straight, but when the segments are 

 separated, as so often happens when the genital segments are 

 being pulled forth and fixed in position, these two plates are fully 

 exposed ; they then appear subcircular. The membranous area at 



