450 NORTH AMERICAN DIPTERA 



Intermediate abdominal segments without discals; a row of orbitals in 

 male (Eupoi!;ona auct.) Eipoj>ona Rondani 



286. Parafacials at least half as wide as median depression, with scattered 



bristly hairs; abdomen largely poUinose 288 



Parafacials less than one-thii'd the width of the median depression, 

 with a row of bristles; abdomen shining 287 



287. Third antennal segment at least twice as long as the second; front 



of both sexes at least two-thirds as wide as either eye (40, 41). 



*Wagneria Desvoidy 

 Third antennal segment but little longer than the second; front 

 strongly narrowed in both sexes fHesperophasia Townsend 



288. Two or three presutural acrosticals and dorsocentrals 289 



No pi'esutural acrosticals and only two pairs of weak presutural dor- 

 socentrals (58, 59) Penthosia Wulp 



289. Proboscis not longer than length of head; parafacials about two- 



thirds as wide as median depression 290 



Proboscis much longer than the head-height; parafacials as wide as 

 the median depression Trochilodes Coquillett 



290. Face receding, longer than the front (84, 85) . . . .Euthyprosopa TowTisend 

 Oral margin prominent, the face shorter than the front. 



Steveniopsis Townsend 



291. Thorax without plumose hairs 292 



Thorax in part with plumose yellowish hairs Teleothyria Wulp 



292. Facial ridges bristled on less than the lower half, the bristles almost 



always decreasing in length above; oral vibrissse always strongly 



developed 341 



Facial ridges with strong bristles on the lower half or more or the 

 vibrissse very weak or absent 293 



293. Oral vibrissse strongly differentiated and long 297 



Oral vibrissge not differentiated 294 



294. Facial ridges with two or three rows of hairs on the lower half, the 



parafacials "rolled" over the ridges above 295 



Facial ridges with a single row of bristles on the lower half, the 

 ridges continuous to the base of the antennae, not hidden on the 

 upper half by the parafacials; presutural acrosticals present 296 



295. Arista pectinate Trixodes Coquillett 



Arista pubescent Trixa Meigen 



296. Apical cell long petiolate; arista about half as long as the third an- 



tennal segment Paraphasmophaga Townsend 



Apical cell short petiolate; arista much longer than antenna (26, 27). 



O^strophasia Brauer & Bergenstamm 



297. Ocellars well developed, directed obliquely forward, rarely almost 



divergent 304 



Ocellars reclinate, absent or scarcely differentiated 298 



298. Ocellars absent or extremely weak 300 



Ocellars reclinate 299 



* Cuiran, 1928, Can. Ent., Ix, p. 48. 

 t Curian, 1927, Can. Ent., lix, ii. 300. 



