J. R. MALLOCH 193 



Gallatin County, Montana, July 24, 1917; Hot Springs, Montana, 

 July 3, 1917; Tennessee Pass, Colorado, July 23, (J. M. Aldrich). 

 Type is in the collection of the U. S. Bureau of Biological 

 Survey. 



Hylemyia bicaudata sp. n. 



Mdlr. — Black, covered with dense drab gray pruinesccnce. Head black, 

 orbits, face and cheeks with dense white pruinescence. Thorax without 

 distinct dorsal vittae, the lateral margins broadly gray pruinose. Dorsum 

 of abdomen with a broad black opaque triangle on each segment; hypopygium 

 distinctly shining; fifth ventral segment glossy. Legs black. Wings slightly 

 grayish. Calyptrae white. Halteres whitish yellow. 



Eyes separated by about the distance between posterior ocelli, the sjiace 

 very much broadened anteriorly; parafacial in profile equal in width to width 

 of third antennal joint and over half as wide as height of cheek; antennae 

 short, third joint but little longer than second; arista almost bare, very much 

 swollen at ba.se. Dorsum of thorax almost devoid of short hairs; post humeral 

 bristle duplicated; presutural acrostichals moderately strong, irregularly 

 two-rowed; prealar bristle usually present, weak, less than half as long as the 

 bristle behind it. Abdomen depressed, the segments subequal, with long, 

 rather spar.se dorsal hairs; apex of abdomen swollen, the fourth visible dorsal 

 segment extending down over sides and overlapping fifth sternite, the latter 

 glossy black, with the posterior lateral angles extended, each armed with 

 a pencil of black, downwardly directed bristles. Fore femur unarmed on 

 antero-ventral surface; fore tibia unarmed at middle; fore tarsus noticeably 

 compressed, almost equal in length to fore tibia; mid femur with a few antero- 

 and postero-ventral bristles on basal half, the latter much the longer; mid 

 tibia with one postero-dorsal bristle near apex; hind femur with a complete 

 series of long, rather widely separated bristles on antero-ventral surface, 

 those on postero-ventral surface much shorter and weaker, confined to basal 

 half; hind tibia with two to four postero-doi-sal bristles, antero-dorsal surface 

 with two to four setulae, antero-ventral surface with or without one or two 

 very short setulae. Third and fourth veins very slightly convergent aiiic- 

 ally; costa slightly thickened at apex of first vein. 



Fctnatc. — Differs from the male in having the interfrontalia reddish and 

 the abdomen unmarked. 



Frons slightly over one-third of the head-width; each orbit half as wide 

 as interfrontalia. Legs similar to those of male, differing in having an antero- 

 dorsal bristle on mid tibia and usually two on the postero-dorsal surface, 

 and the postero-ventral surface of the hind tibia bare. The costa is mon> 

 noticeably swollen than in the male. 



Length, 2.75 to 3. .5 mm. 



Tijpe.—d'] Grand Tower, Illinois, April 21, 1914, on hank of 

 Mississippi River, (J. R. Malloch), [Illinois]. Allotype— 9 \ 

 Widewater, Virginia, April 2, 1916, on flowers of Salix trislia, 



TKANS. .\M. ENT. SOC, XLVI. 



