330 ERNEST A. BACK 



projecting. Thorax broad, almost quadrangular, rather 

 arched. Abdomen very broad, flattened, clearly punctate, 

 on the tergum with much shorter pile, on the sides with hair 

 in tufts, on the venter with longer and denser pile. Legs 

 rather stout, with thicker longer hair and bristles intermixed; 

 the metatarsi not much elongated ; the pulvilli normal. Mid- 

 dle tibiae of male sometimes with a brush of bristles and hair 

 on the anterior sides ; the fore tibiae without a terminal claw- 

 like spur. The anterior branch of the bifurcate third longi- 

 tudinal vein with a supernumerary vein, not always present; 

 fourth posterior cell wide open, narrowed, or closed; the other 

 posterior cells wide open; the anal cell closed on the margin 

 or narrowly open. 



Type. — Dasypogon apifornis Loew. 



The differences between this genus and Heteropogon are very 

 slight. The shape of the head, antennae and venation are the 

 same, but the abdomen in the typical species is broader, 

 rather shorter and very densely pilose on the sides and venter. 

 Schiner states that the species have somewhat of a "bee-like" 

 appearance and this does seem to be the case with Osten 

 Sacken's cirrahatus. The same tibial brush is found in some 

 of the males of this genus as well as in some of those of Heter- 

 opogon. If Mr. Coquillett's determinations are correct, senilis 

 Bigot is a good Heteropogon. Mr. Coquillett's divisus is an 

 excellent example of this genus, as also is Dr. F. Hermann's 

 leucostomus. 



Pycnopogon cirrliatus (PI. X, fig. 8). 



Pycnopogon cirrahatus Osten Sacken, Western Dipt., 293, 1877. 

 ? Pycnopogon cirrhatus Williston, Trans. Am. Ent. Soc, XI, 15, 



1884. 

 Pycnopogon cirrhatus Jones, Trans. Am. Ent. Soc, XXXIII, 

 279, 1907 (note). 

 "(J^. — Length 8.5 mm. — Black; thorax with white hairs; abdomen 

 with recumbent, golden-yellow pile, especially dense on its latter part; 

 femora black; tibiae red; middle tibiae before the middle with a tuft 

 of black pile. 



"Head and face clothed with white pile; some black bristles above 

 the mouth and also on the upper part of the occiput. Thorax black 

 (the dorsum is greasy on my specimen), with long, soft, white pile; 

 the usual bristles black. Halteres lemon-yellow; trichostical pile rather 



