240 Annals Entomological Society of America [Vol. XV, 



above, on the postalar callosities and on the margin of the scutellum, 

 which is rather large, squarish or more or less triangular. Abdomen 

 roughly triangular in shape, broader, and not much longer than the 

 thorax, broadest at the second segment, thence quickly narrowing to 

 the apex, but less so in the female. Legs simple, the femora a little 

 strengthened, and usually with short bristles below, especially the hind 

 pair. Wings longer than the abdomen, anterior cross-vein before the 

 middle of the discal cell, first posterior cell ending in an acute angle 

 near the apex of the wing. Squamae of medium size. 



GENERIC RELATIONSHIP AND LIMITATION. 



It seems that this genus cannot really claim close relationship 

 to other genera found in North America, although certain 

 characters indicate a common origin with several genera. 

 In Europe it is even more isolated. I cannot agree that 

 Hammer schmidtia is very closely related, because in that 

 genus the wing venation is quite distinct, the face bears a 

 distinct tubercle in the male, the tibiae are all armed with 

 spines, as are the femora, and the thorax and ^cutellum bear 

 strong bristles. The fact that both may possess plumose 

 arista does not constitute a close affinity. 



It is perhaps as well to clear up the question of these two 

 genera here. I would distinguish betw^een them as follows: 

 In Hammer schmidtia the abdomen is slender, twice as long as 

 the thorax; the face is tuberculate in the male; thorax armed 

 with very evident spines; the legs are armed with spines and 

 the anterior four tibiae terminate in a row of bristles; the 

 first posterior, cell is not acute, and ends well from the apex 

 of the wing. In Brachyopa the abdomen is triangular, only 

 a little longer than the thorax, the face is concave in both 

 sexes, the thorax has sometimes very small bristles, the legs 

 may have spines below the femora, but not elsewhere; the first 

 posterior cell is acute and ends near the apex of the wing. 

 Thus it will be seen that even leaving the plumosity of the 

 arista out of consideration, there are ample grounds for 

 separating the two genera. 



The genus which appears to be most closely allied to 

 Brachyopa is Chal corny ia, notwithstanding the separated eyes 

 in the latter genus. The shape of the abdomen is very similar, 

 the eyes of i^everal species of Brachyopa are not actually con- 

 tiguous, the facial profile is more similar, and the wing venation 

 is identical. Moreover, I have taken representatives of both 



