442 NORTH AMERICAN DIPTERA 



168. Penultimate aristal segment elongate Paradmontia Coquillett 



Penultimate aristal segment very short, the arista strongly thickened 



at the base Websteriana Walton 



169. Posterior tibise evenly and closely ciliate with bristles; hair of para- 



facials fine 170 



Posterior tibiae not ciliate or the parafacial hair coarse 171 



170. Facial ridges bristled on almost the lower half. . . .Sturmiopsis Townsend 

 Facial ridges bristled on net more than the lowest third (145, 162). 



* Winthemia Desvoidy 



171. Parafacials with bristly hair or a row of bristles 172 



Parafacials with two bristles below Chromatocera Townsend 



172. Ocellars proclinate (42, 43, 45, 52, 96). 



Paradidyma Brauer & Bergenstamm 

 Ocellars reclinate (155) Ricosia Curran 



173. Third antennal segment not more than twice as long as the second. . .178 

 Third antennal segment more than twice as long as the second 174 



174. Apical cell long petiolate 175 



Apical cell not long petiolate 176 



175. First vein setulose on basal half Paradmontia Coquillett 



First vein bare Mauromyia Townsend 



176. Penultimate aristal segment short 177 



Penultimate aristal segment elongate; pai-afacials with two bristles 



below Chromatocera Townsend 



177. Two presutural acrosticals Ictericophyto Townsend 



Three presutural acrosticals (111) Gaediopsis Brauer & Bergenstamm 



178. Second antennal segment, if elongate, clothed with sparse, fine bristly 



hairs on the upper surface 179 



Second antennal segment as long as the third, very densely bristled 

 above; cheeks one-third as wide as the eye-height (105). 



Muscopteryx Townsend 



179. Vibrissse situated on a level with the oral margin 180 



Vibrissge situated well above the oral margin; parafacials almost as 



wide as the third antennal segment Meriana Desvoidy 



180. Ocellars absent; prosternum bare. .Bombyliomyia Brauer & Bergenstamm 

 Ocellars long, though weak, prosternum pilose Tachinalia, n. g. 



181. Palpi of normal length and shape, if apparently short, broadened 



apically ' 182 



Palpi short and narrow, seldom twice as long as thickness of proboscis 

 at point of attachment; bend of fourth vein with appendage (77). 



Linnaemya Desvoidy 



182. Facial ridges with strong bristles on lower half or more 183 



Facial ridges with bristly hairs decreasing in length upwardly, rarely 



extending almost half way 204 



183. Ocellars long, readily distinguished 190 



Ocellars absent or hair-like 184 



* Reinhard, 1931, Pr. U. S. N. M., Ixxix, Art. 20, pp. 1-54. 



