460 NORTH AMERICAN DIPTERA 



Parafrontals wide, the median vitta less than one-fourth as wide as 

 the parafrontals at the middle; ocellars absent; front gently convex. 



Arsyrophylax Brauer & Bergenstamm 



421. Oral margin rather strongly produced Siphosturmia Coquillett 



Oral margin but slightly produced Sturmia Desvoidy 



422. Face at least moderately retreating 449 



Face but little retreating, almost or quite as long below as at base of 



antennae 423 



423. Apical section of the proboscis much shorter than the head-height or 



the apical cell ending far before the wing-tip 427 



Apical section of the proboscis at least as long as the head-height; 

 apical cell ending close to the wing-tip 424 



424. First vein bare above 425 



First vein setulose above Leskiomima Brauer & Bergenstamm 



425. Arista bare or pubescent 420 



Arista with very long rays (176, 185) Shermanalia, n. g. 



426. Head decidedly higher than long (14, 82, 150, 174) .Epigrimyia Townsend 

 Head as long below as its height Weberia Desvoidy 



427. Parafacial decidedly less than half as wide as the facial depression; 



face not strongly carinate 432 



Parafacial at the narrowest part almost or quite half as wide as the 

 facial depression, or the face strongly carinate 428 



428. Arista long plumose 429 



Arista pubescent or bare Apachemyia Townsend 



429. Facial carina weak (128, 131) Zelia Desvoidy 



Facial carina strong 430 



430. Antennae reaching little more than half way to the oral margin 431 



Antennae reaching three-fourths of the way to the oral margin (120, 



129 ) Scotiptera Macquart 



431. Third antennal segment three times as long as the second. 



Eudexia Brauer & Bergenstamm 

 Third antennal segment not three times longer than wide, in the male 

 only slightly longer than the second (127, 130) . .Hystrichodexia Roder 



432. Apical cell ending in or near the wing-tip 435 



Apical cell ending well before the wing-tip 433 



433. Third vein with only a few basal bristles 434 



First and fifth veins bristled above (123) Thelaira Desvoidy 



434. Frontal vitta not wider than either parafrontal Demoticus Macquart 



Frontal vitta twice as wide as either parafrontal; a row of orbital s. 



Euhalidaya Walton 



435. Third antennal segment near the base not wider than the second, or 



if so, the abdomen elongate and narrow 437 



Third antennal segment conspicuously wider than the second; abdo- 

 men short, oval 436 



436. Presutural acrosticals scarcely developed. . . . Chaetostigmoptera Townsend 

 Presutural acrosticals well developed (148, 189) *Actia Desvoidy 



* Curran. 1933, Amar. Mus. Movit. No. 614, pp. 1-7. 



