gg. No orbitals; height of bucca about a third less than height of eye. West U. S. _C. wheeleri_ Hough ff. Body black or sordidly metallic greenish gray, usually yellow pollinose or variegate; genæ at most hairy above. _N. stygia_. Eastern Hemisphere. _Neopollenia_ Br. dd. Vibrissal angle situated nearly on a level of the oral margin. e. Species wholly blackish, bluish, or greenish metallic in color. f. First section of R_{4+5} with at most three or four small bristles at the immediate base. g. The bend of M_{1+2} a gentle curve; costal spine present; cell R_5 closed, ending before the apex of the wing. _S. cuprina._ Java. _Synamphoneura_ Bigot gg. Bend of M_{1+2} angular; or the insect differs in other characters; dorsal surface of the squamula thoracalis hairy (except in _Melinda_); arista plumose only on the basal two-thirds (except usually in _Calliphora_ and _Eucalliphora_). [Illustration: 168. Head of horn-fly (Lyperosia irritans); (_a_) female; (_b_) male; (_c_) lateral aspect of female. Bureau of Entomology.] h. Arista plumose only on the basal two-thirds. i. Base of the antennæ ventrad of the middle of the eye; eyes of the male nearly contiguous; genæ hairy; second abdominal segment with median marginal macrochætæ; two, rarely three, postsutural intraalar macrochætæ. j. Squamula thoracalis dorsally with long black hairs; male hypopygium two-segmented, large, projecting; claws and pulvilli of the male elongate; three strong sternopleural macrochætæ; genæ at least half the width of the eye; buccæ (cheeks) half the height of the eyes; oviviparous. _O. sepulcralis._ Europe. _Onesia_ R. D. jj. Dorsal surface of the squamula thoracalis bare; male hypopygium small, scarcely projecting below; claws and pulvilli not elongate; two stout sternopleural macrochætæ, sometimes with a delicate one below the anterior; genæ nearly linear in the male; buccæ about a third of the eye height; oviparous. _M. cærulea_. Europe. _Melinda_. R. D. [Illustration: 169. Lateral and dorsal aspects of the thorax, and frontal aspect of the head of a muscoidean fly, with designations of the parts commonly used in taxonomic work.]