h. R_{4+5} does not form an angle at the crossvein. On birds. There is a record of one species of this genus attacking man. ORNITHOMYIA Latr. hh. R_{4+5} makes an angle at the crossvein. _O. confluens_. _Ornithoica_ Rdi. ff. Anal cell not closed by an anal crossvein. _Lynchia_, _Pseudolfersia_, and _Olfersia_ are chiefly bird parasites. The first mentioned genus is said to be the intermediate host of _Hæmoproteus columbæ_. aa. Abdominal segments chitinous; not parasitic in the adult stage. b. Antennæ with six or more segments and empodium not developed pulvilliform; palpi often with four segments. c. Ocelli present. BLEPHAROCERIDÆ, RHYPHIDÆ, BIBIONIDÆ, MYCETOPHILIDÆ, besides some isolated genera of other families. cc. Ocelli absent. d. Dorsum of the thorax with a V-shaped suture; wings usually with numerous veins; legs often very long and slender. Crane flies. TIPULIDÆ dd. Dorsum of the thorax without a V-shaped suture. e. Not more than four longitudinal veins ending in the wing margin; wing usually hairy: antennæ slender; coxæ not long; tibiæ: without spurs, legs long and slender. Small, delicate flies often called Gall gnats. CECIDOMYIIDÆ. ee. More than four longitudinal veins ending in the wing margin. f. The costal vein is not produced beyond the tip of the wing; radius with not more than three branches. g. Antennæ short, composed of ten or eleven closely united segments; legs stout; body stout; abdomen oval; anterior veins stout, posterior ones weak (fig. 163 b); eyes of the male contiguous over the antennæ. Black flies, buffalo flies, turkey gnats. Many North American species, several of them notorious for their blood sucking propensities. SIMULIIDÆ h. Second joint of the hind tarsus with basal scale-like process and dorsal excision (fig. 161 h); radial sector not forked; no small cell at the base of the wing. _S. forbesi_, _jenningsi_, _johannseni_, _meridionale_, _piscicidium_, VENUSTUM, VITTATUM, etc. Widely distributed species (= EUSIMULIUM) SIMULIUM Latr. hh. No basal scale-like process on the second joint of the hind tarsus; radial sector usually forked (fig. 163 b). i. Face broad, small basal cell of the wing present. _P. fulvum_, HIRTIPES, _mutatum_, PECUARUM, _pleurale_. PROSIMULIUM Roub.