166 ERNEST A. BACK. 



Scutellum black, white pruinose. The black of the mesonotum, scutel- 

 lum and the lower portion of the pleurae is variable and the black spot 

 on the dorsum of the type specimen is not at all clearly defined. Abdo- 

 men yellowish, the first segment and the posterior margins of the 

 several following segments polished black; the median vittae of the 

 last three segments black; pile of all the segments white. Legs dull 

 yellow, the obsolete subapical ring of the third hind femora and the 

 apex of the hind tibiae brownish; the apex of the distal segments of 

 the tarsi black. Claws black; empodia present. Wings hyaline, 

 tinged with yellow, violaceous, the second submarginal cell equal twice 

 the length of the peduncle, second posterior cell moderately elongate, 

 the fourth pedunculate. 



Type. — M. C. Z. Single male type. 



Habtiat— 111. (type); N. Y.; Riverton (July 30; Aug. 11, 

 13, C. W. Johnson), and Atco, N. J.; Phila. (June 11), Pa.; 

 Milwaukee (June 24), Wis. 



This species is closely allied to flavipes in general appearance 

 and is sometimes mistaken for it. The above description was 

 made from eight specimens, including the type male. 



Leptogaster niurinus. 



Leptogaster murinus Loew, Cent., II, 9, 1862. 

 Leptogaster murinus Jones, Trans. Am. Ent. Soc. Phila., 

 XXXIII, 273, 1907 (locality note). 



cf 9- — Length 12-14.5 mm. — Rather larger grayish-brown species, 

 the thoracic dorsum deep brown pruinose, in sharp contrast to the 

 white pruinose pleurae. Antennae and bristles of upper occiput black; 

 abdomen not ringed; legs clear yellow, the posterior femora on distal 

 portion and the distal half of their tibiae reddish-brown or blackish. 



Face and mystax white; the front and occiput brownish pruinose; 

 bristles of the occiput black, extending along the orbits, but stoutest 

 on the upper part. Proboscis black. Antennae polished black, some- 

 times tinged with reddish; second segment rounded; the third elongate 

 oval, shaped somewhat like an Indian club, the bristle-like style 

 attached to its handle, and about one-half as long. Thorax black, 

 well arched; the dorsum with a dark brownish bloom almost obscuring 

 the geminate stripe, and paler on the posterior part before the scutel- 

 lum; the pleurae and coxae white pruinose and stands out in sharp 

 contrast to the brownish dorsum. Halteres with blackish knob and 

 whitish peduncle. Abdomen ringed, brownish pruinose, subopaque, 

 more grayish toward its lateral margins. Legs clear yellow, polished; 

 hind femora only gradually thickened distally, upon distal portion 

 with a short reddish-brown or blackish stripe before and behind; the 

 distal half of the hind tibiae likewise reddish-brown; the metatarsi 



