AMERICAN DIPTERA. 155 



36. Abdomen flattened, in the female a little broader beyond the 

 middle ; in the male very flat, much broader near tip 

 (PI. II, fig. 8), seventh and eighth retracted within the 

 sixth and not visible from above; the fifth and sixth seg- 

 ments above conspicuously silvery and bearing on each 



side five distinct punctures (PI. X, fig. 2) NlCOCles. 



Abdomen not at all expanded as above (PI. XI, figs. 3, 4; VIII, 5). 



Copliura. 

 LEPTOGASTRIN^. 



The Leptogastrinae in America, north of Mexico, is repre- 

 sented by the single genus Leptogaster. 



LEPTOGASTER. 



(PI. VI, Fig. 1.) 

 Leptogaster Meigen, Illig. Mag., II, 269, 1803. 



" Asiles tipuloides," Latreille, Hist. Nat. Crust, et Ins., IV, 1802. 

 Gonypes Latreille, id, XIV, 309, 1804. 

 Gonypes Latreille, Dictionaire d' Histoire naturelle de Deterville, ed. 



I, 1804. 

 Leptogaster Meigen, Syst. Beschr., II, 258, 1820. 

 Gonypes Macquart, Hist. Nat. Dipt. I, 315, 1834. 

 Leptogaster Zetterstedt, Dipt. Scand., 1, 186, 1842. 

 Leptogaster Schiner, Fauna Austr. I, 117, 1862. 

 Leptogaster Williston, Biologia, Dipt., 298, 1901. (Partial table of 



Mexican species.) 



Very slender, abdomen very elongate, almost bare species 

 of from small to medium size. Marginal cell of wing open; 

 five posterior cells present, all open; third segment of the 

 antennas with a bristle-like style. Legs without pulvilli, the 

 empodia in form of a stout bristle, or, rarely, absent; tibiae 

 without terminal claw-like spear. 



The large eyes occupy nearly the entire head, leaving only 

 a very narrow face without gibbosity and with mystax thin 

 and confined to the oral margin; proboscis short. Front and 

 vertex well depressed, ocellar tubercle distinctly elevated. 

 Antennas approximate, the first and second segments sub- 

 equal in length, but the second more robust than the first; 

 the third segment more or less elliptical, sometimes more 

 elongate, usually somewhat compressed; style bristle-like, 

 longer or shorter than the third segment, often composed of 

 two parts, and, together with the third segment, pubescent in 



TRANS. AM. ENT. SOC, XXXV. MAY, 1909. 



