192 INTRODUCTION TO ZOOLOGY. 



CC— Dorsum of tlie thorax withoiit a V-shaped suture. 



D A complete cliscal cell present (Rhyphidae.) 



DD~No discal cell. 

 E— Antennas composed of three joints, with a terminal arista. 



(Orphnephilida3. ) 

 EE— Antennse apparently not composed of three joints and a terminal 

 arista. 

 F— Wings with only a few longitudinal veins and no cross veins. 



(CecidomyidEe.) 

 FF — Wings usually many-veined. 

 G— Ocelli present. 

 H— Wings broad, hare, marked "by numerous folds between the 

 veins, giving a nei-ued, spider weh-like appearance. 



(LiponeuridEe.) 

 HH— Wings not so marked. 



I— Coxas much elongated (Mycetophilidae. } 



II— Coxae short (Bibionidaj.) 



GG— Ocelli wanting. 



H— Costal or marginal vein not extending beyond the tip of the 

 wing. 

 I— AntennaB slender, the joints more or less constricted, and often 

 bushy plumose; legs slender, hind tibiae and metatarsi never 



dilated; abdomen slender ; wings narrow (Chironomid^.) 



II— Antennas shorter than the thorax; never hairy; legs strong, 

 hind pair dilated ; body thick-set; wings broad. 



(SimuliidEB.) 

 HH— Marginal vein encompassing the whole wing. 

 I— Wings ovate, with ten longitudinal veins and no cross veins. 



(Psychodidae.) 

 II— Wings with cross vein near the middle. 

 J — Wings hairy, fringed on the margin. Mosquitoes. 



(Culicidae. ) 

 JJ— Wings bare; the second vein arises near the middle of the 



wing (Dixidie.) 



BB— Third joint of antennae complex; basal cells of the wing long. 

 C— Empodia developed pulvilliform. 

 D— Alulae rather large; third longitudinal vein forked. Horseflies. 



(Tabanidae.) 

 DD— Alulae small or rudimentary. Mostly flower flies. 

 E— TibiK wholly without spurs; costal vein not reaching beyond the tip 



of the win^ (StratiomyidiB. ) 



EE— Middle tibise, at least, with spurs; costal vein encompassing the 



whole wing .^ (Leptid^.) 



BBB— Antenna composed of three simple joints. 

 C— Antennae apparently composed of a single joint with a long bristle ; femora 

 flattened, hind legs long. Small, quick-running, hump-backed flies. 



(Phoridge.) 

 CC— Not such flies. 

 D— Empodia developed pulvilliform; that is, three nearly equal membra- 

 nous appendages on the under side of the claws. 



E— AlulEe very large (Acroceridse.) 



EE— Alulae of moderate size or rudimentary. 

 F— Middle tibiae, at least, with spurs; no bristles on femora or tibiae; 

 third longitudinal vein forked; five posterior cells present; an- 

 terior cross vein always distinct; third joint of the antennae ^^lth 



a bristle, or sk-nder style, usually terminal (Leptidae. ) 



FF— Not such flies. 

 G— Third longitudinal vein forked, two or more submarginal cells 

 present. 

 H— Arista, or style of antennae, always present and dorsal. 

 I— Head comparatively small; proboscis more or less elongated. 



(EmpidEe. ) 

 II— Head as broad as the thorax; i:)roboscis fleshy.. (Platypezidse.) 

 HH— Arista terminal or absent. 



I— Vertex and front distinctly hollowed out between the eyes. 

 Mostly large flies. 

 J— Proboscis with fleshy labellas at the tip; palpi rudimentary 

 or wanting (Mydaidae.) 



