AMERICAN DIPTERA. 283 



the stigma being shorter than the fourth section of costa, 

 should distinguish it among those with non-cleft hypopygium. 



2. P. affluis n. sp. 



cT. Front and face silvery; occiput brownish or grayish ; antennae 

 black, but third joint brownish, long white acuminate. Mesonotum 

 rather opake, brownish, more or less cinereous along margins; scu- 

 tellum concolorous. Pleura and metanotum cinereous to nearly white ; 

 humeri yellow; knobs of halteres black or brown, with brown or 

 yellow pedicles. Abdomen subcylindrical, opake to subopake, brown- 

 ish ; apical margins and ventral margins of segments cinereous ; 

 fifth longer than fourth. Hypopygium (Fig. 80) small, cinereous 

 tinged, not cleft ; lateral and intermediate lobes just visible at extreme 

 left ; ventral lobe yellow. Legs slender ; coxa?, femora except bases 

 and apices, more or less developed ; tibial ring, and apical joint of tarsi, 

 black, otherwise the legs are yellow; inner surface of post-femora 

 polished ; spines weak ; post-tibia? slightly swollen at the middle, 

 nearly straight. Wings (Fig. 166) grayish; stigma colored. Length, 

 3.8 mm. ; wings, 4.4 mm. 



9 . Similar to male, with front entirely silvery to the vertex ; broad 

 margins of mesonotum cinereous, leaving only the disc brown ; scutel- 

 lum also more grayish ; sixth abdominal segment shorter than fourth, 

 with a distinct longitudinal groove on middle of dorsum, entirely gray- 

 ish tinge ; ovipositor (Fig. 81) yellow, very short, hardly reaching apex 

 of fifth ventral segment, abruptly terminating its broad, short, gray- 

 ish tinged base, which hardly protrudes beyond the sixth segment. 

 Wings are very long in proportion. Length, 3.8 mm. ; wings, 6.0 mm. 



Type. — o". Cottage Beaulieu, Beaulieu, Quebec, June 14, 

 1906 (Figs. 13, 166, Beaulieu, coll. Johnson). 



Paralypes.— St. Johnsbury, Vt., 1 c? ; Burlington. Vt., 1 9 , 

 Fig. 81 ; Barnstable, Mass., 1 9 (all by Johnson, B. S. N. H.); 

 Great Falls, Va. (1 9, coll. Banks). Taken in June and 

 July. 



The males of this species seem to agree with those con- 

 sidered by Dr. Hough to be subopacus Loew, but the females 

 do not agree with his description as to the ovipositor ; and 

 it does not seem probable that I have separate species in the 

 two sexes before me. Dr. Hough (1899 Hough 79) de- 

 scribes the abdomen as brown-black, almost shining, with 

 apices of segments whitish pollinose ; halteres yellow ; 

 femora black, with apex sometimes yellow, tibia? varying 

 from yellowish with black rings, to black with yellowish 



TRANS. AM. ENT. SOC.XXXVI. (36*) DECEMBER, 1910. 



