172 ERNEST A. BACK. 



while in the type specimen this yellow is practically obsolete; 

 the fourth posterior cell of one of the wings (the other is 

 wanting) is sessile. 



Leptogaster tenuipes. 



Leptogaster tenuipes Loew, Cent., II, 14, 1862. 



C? 9- — Length 9.2-10 mm. — Brown, subpolished; hind femora and 

 tibias unusually slender; antennae blackish; thorax reddish, dorsum 

 with a large dead-black spot; wings hyaline, sometimes darker on the 

 basal portion, the second submarginal cell equal in length to its 

 peduncle. 



Face white pruinose, mystax of same color. Antennae black, the 

 basal segments fuscous; the third segment rounded at base, gradually 

 tapering toward tip, shorter than the black bristle-like style. Occiput 

 without stout bristles but with white pile below. Thorax reddish, but 

 covered by a thin whitish bloom; the three dorsal stripes run together 

 to form a large dead-black spot covering the larger part of the dorsum. 

 Bristles on the posterior callosities black, as also is the fine hair of the 

 dorsum; the anterior portion of the meso- and sternopleuras with prom- 

 inent white pile. Halteres yellowish, the knobs darker. Abdomen 

 brown, towards the apex blackish, not ringed; the very fine hair on 

 the sides white. Legs slender, very slightly testaceous, the anterior 

 sides of the femora and tibiae darker; the metatarsi at tip, and the 

 larger part of the other tarsal segments darker. The hind legs are 

 unusually slender; the femora have a very long, slender basal portion 

 which distally becomes only gradually incrassate, without distinct 

 markings; their tibiae likewise very slender and terminated on the 

 inner side with two or three white bristles; rest of bristles of legs, 

 black. Wings hyaline, in the female and sometimes in the male, the 

 basal third is perceptibly darkened; veins blackish; the second sub- 

 marginal cell equal in length to its peduncle, the second posterior not 

 much elongated, the fourth pedunculate. The anterior intercalary 

 forms a rather indistinct angle with that portion of the posterior 

 cross- vein which closes the second posterior cell behind. 



Type. — M. C. Z. One male specimen. The female men- 

 tioned in the note of the original description is also there. 



Habitat. — D. C. (type); Del. ; S. Ga. ; Tex. The Delaware 

 specimen is at the Am. Ent. Soc. of Phila; those from Georgia 

 and Texas are at the National Museum. 



Leptogaster testaceus. 



Leptogaster testaceus Loew, Cent., II, 10, 1SG2. 

 ? Leptogaster rubidus Wiedemann, Auss. Zwei., I, 533, 1828. 

 f Leptogaster rubida Williston, Biologia, Dipt., I, 299, 1901, 

 (thinks rubida and testaceus may be the same). 



