2I y 



Third joint of antennae more than twice the length of the first, 

 bulbous at the base. ........ 34 



34. The origin of the second section of the second vein is before the 



proximal end of the discal cell in an acute angle.. . . 35 

 The origin of the second section of the second vein is beyond the 

 proximal end of the discal cell and is rectangular. 



Desmatoneura. 



35. Third antennal joint scarcely longer than wide. . Eucessia. 

 Third antennal joint much longer than wide. ... 36 



36. Face projecting in profile. ..... Epacmus. 



Face retreating in profile. .... Aphcebantus. 



37. Ocellar tubercle situated near vertex. ..... 38 



Ocellar tubercle situated near middle of front. Metacosmus. 



38. Antennae elongate, third joint flattened, the style broad and dis- 



tinctly composed of two segments (B, 9, p. 80, type) . 



Desmatomyia. 

 Antennae not elongated nor with such a style. Paracosmus. 



39. Slender, elongate species, with slender legs. ... 40 

 Shorter, more thick-set species, the abdomen never cylindrical. 41 



40. Both males and female holoptic; abdomen enlarged at extremity 



(fig. 82, 23, 24) Systropus. 



Males holoptic, the females dichoptic; abdomen cylindrical, not 

 enlarged at extremity (11, p. 80) . . . Dolichomyia. 



41. Three submarginal cells. ....... 42 



Two siibmarginal cells (18, 19, 2O) Geron. 



42. Body clothed with more scales than hairs, usually with thoracic 



bristles; abdomen decumbent; antennae long (21, 22) . 



Toxophora. 

 Body clothed chiefly with hair; abdomen not decumbent. 



Rhabdopselaphus . 



