124 
Psyche 
[June 
curved than in B. tenuipes. Legs brown, slender, middle 
femur a tenth longer than the fore femur; tibiae and com- 
sponding tarsal segments of fore and middle legs subequal, 
the measurements for the middle leg beginning with the 
femur being 2.8, 2.4, 1.4, 0.6, 0.4, 0.25, 0.25 mm. Hind legs 
wanting in the type specimen. Wing clear hyaline, irides- 
cent; length from basal articulation, 4.5 mm. Halteres 
yellow with brown knob. Length of fly 4 mm. Amherst, Mas- 
sachusetts, June 25, 1927. Dr. C. P. Alexander, Collector. 
Aside from the difference in the form of the hypopygium 
as noted above, this fly differs from B. tenuipes in having 
a distinctly shining thorax, in the proportion of its tibia 
to basitarsus being 12 to 7 instead of 12 to 6, in the sides of 
the face being more nearly straight and in the hairs on the 
base of the claws being less conspicuous. 
I am indebted to Mr. F. W. Edwards for submitting this 
fly to me for description. Several specimens in the British 
Museum, type in the Cornell University collection. 
