m. Proboscis geniculate, inserted in a deep slit; female without extricate ovipositor; arista either bare or plumose; squamæ large; facial grooves approximated below. n. Arista bare, short. Larvæ in rodents. Tropic America. _B. princeps_. _Bogeria_ Austen nn. Arista pectinate above. o. Tarsi broadened and flattened, hairy, anal lobe of the wing large. Larvæ in rodents. A number of American species. _Cuterebra_. oo. Tarsi slender, not hairy; anal lobe of the wing moderate. Larvæ in man and other mammals. Tropic America. D. CYANIVENTRIS. DERMATOBIA Br. mm. Mouth parts very small, vestigial; arista bare. n. Facial grooves approximated below, leaving a narrow median depression or groove. o. Cell R_5 closed and petiolate, body nearly bare. Larvæ in the nasal cavities of the smaller Ungulates. The sheep bot fly. O. OVIS. Widely distributed OESTRUS L. oo. Cell R_5 narrowly open, body hairy. Larvæ parasitic on deer. Europe and America. _Cephenomyia_ Latr. nn. Facial grooves far apart, enclosing between them a broad shield-shaped surface; squamæ large; female with elongate ovipositor. Larvæ hypodermatic on Ungulates HYPODERMA Clark o. Palpi wanting; tibiæ thickened in the middle. p. Hair at apex of the abdomen yellow; legs including femora yellowish brown. H. DIANA pp. Hair at the apex of the abdomen reddish yellow. Europe and America. q. Tibiæ and tarsi yellow; femora black. H. LINEATA qq. Legs black with black hair; tips of hind tibia and tarsi yellowish brown. H. BOVIS