mm. R-m crossvein present.
n. Fore femora very much swollen, armed with spines below, fore tibia arcuate and applied closely to the inferior margin of the femur.
o. R2+3 present, therefore cell R1 and R2 both present; wing usually fasciate. United States. Heteromyia Say.
oo. R2+3 not distinct from R4+5, hence cell R3 obliterated. South America. Pachyleptus Arrib. (Walker)
nn. Fore femur not distinctly swollen.
o. R2+3 present therefore cells R1 and R3 both present, or if not, then the branches of the radius more or less coalescent, obliterating the cells.
p. At least the tip of the wing with erect setulæ; tip of R4+5 scarcely attaining the middle of the wing, empodium rather indistinct, not reaching the middle of the claws, the claws not toothed, equal, with long basal bristle; legs without stout setæ. Widely distributed. Culicoides Latr.
Hæmatomyidium and Oecacta are probable synonyms of this.
pp. Wings bare, if rarely with hair, then the radius reaches beyond two-thirds the length of the wing, or the femur or fifth tarsal segment with stout black spines.
q. Media unbranched. Europe. Brachypogon Kieff