202 NORTH AMERICAN DIPTERA. 



Ul'HRIN^E. 



Marginal cell closed, antenna with or without a terminal style, n<>t with <> 



ii rminal bristle. 



i. Front tibiae with a terminal, claw-like spur. .... 2 

 Front tibiae not with such spur. ...... 3 



2. Thorax projecting prominently in front (21, 41). Pseudorus. 

 Thorax not projecting prominently in front.* . Doryclus. 



3. Veins at distal ends of the discal and fourth posterior cells paral- 



lel or continuous in the same straight line. ... 4 



Veins at distal ends of discal and fourth posterior cells very dis- 

 tinctly angulated and not parallel. ..... 7 



4. Third joint of antennae with a terminal style, in length greater 



than the first two together; eyes not or but slightly emarginated 

 on the sides of the front, the front much wider above; scutellum 



without bristles, or with hairs: small species (42). Atonia. 

 Third antennal joint without terminal style. ... 5 



5. Third joint of antennae at least three times as long as the first two 



together; rather large species. . , . . Aphestia. 



Third antennal joint not more than twice the length of the first 



two combined; small species. . . ... . . 6 



6. First antennal joint more than twice the length of the second; front 



much widened above, the eyes disciform and with enlarged fa- 

 cets in front; scutellum with weak bristles ; body punctulate 



(44 1. Cerotainia. 



Third joint of antennae not more than twice the length of the sec- 

 ond; eyes on the sides of the front emarginate, the front not 

 widened above; scutellum with bristles; first posterior cell usu- 

 ally narrowed; body punctulate (22, 43) . . Atomosia. 



7. Three submarginal cells present; first posterior cell closed or nar- 



rowed (23). Pogonosoma. 



Two submarginal cells. ........ 8 



8. Antennae with a distinct terminal style. .... 9 

 Antennae not with a terminal style. ..... 10 



9. Rather small, nearly bare species, with pollinose spots or lascias 



on the abdomen; first posterior cell open or closed (see Dasypo- 

 goninae, 16; Laphyslia.) 



* The distinction between these two genera seems doubtful to me. 

 Megapoda is a distinct genus, characterized by the hind tibiae and 

 metatarsi not being thickened; the name is not preoccupied. 



