294 



7. Generally more than one pair of femora with spines; neither fore 



nor hind femora noticeably thickened Palpomyia (p. 319). 



— Only fore or hind femora with spines, the spinose pair perceptibly 



thickened 8 



8. Fore femora thickened and spinose Heteromyia (p. 324). 



— Hind femora much thickened and spinose. . . .Serromyia (p. 331). 



9. Media sessile Joliannsenomyia (p. 332) . 



— Media petiolate Hartomyia (p. 339) . 



10. At least one pair of femora with ventral spines 11 



— Femora not spinose 12 



11. Media sessile Bezzia (p. 345). 



— Media petiolate Pseudohezzia (p. 351). 



12. Media sessile Prohezzia (p. 352). 



— Media petiolate Parahezzia (p. 358) . 



N. B. The genus Atrichopogon is distinguished by the bare wings and distinct 

 empodia. I have seen no species belonging to this genus. 



Keys to Larv/E and Pup^e of North American Species 



OF CeRATOPOGON and FORCIPOilYIA* 

 LARV^ 



1. Body slightly flattened, deep lateral incisions between the abdominal 



segments, each segment with a lateral, pointed elongation, as shown 

 in Figure 4, Plate XVII, body bristles simple, neither lanceolate 

 nor branched C. fusculiis. 



— Body rounded, in cross-section, incisions between the segments not 



deep, body bristles not all simple 2 



2. Dorsal bristle and the anterior one of the dorso-lateral pair thick- 



ened at base, tapering to well beyond the middle 



F. stenammnfus* 



— Dorsal bristle spear- or club-shaped, thicker beyond middle than at 



base 3 



3. One dorso-lateral bristle, the usual posterior dorso-lateral one being 



on a horizontal level with the lateral bristle, so that there may be 



said to be 2 lateral bristles F. hnnnalis* 



F. cilipes. 



— Two dorso-lateral bristles present, situated on a distinct ridgelike 



prominence, lateral bristle much below the level of both 4 



4. Dorsal bristles very short and leaf like F. ivlieeleri* 



— Dorsal bristles elongated, at least six times as long as their greatest 



breadth 5 



5. Dorsal bristle club-shaped, or spatulate, the broadest part beyond 



middle 6 



— Dorsal bristle spear-shaped, its broadest part slightly before the 



middle (PL XVIII, Fig. 17) F. speciilaris. 



'Species marked with an asterisk are unknown to me except by description. 



