J. R. MALLOCH 143 



1913; Bozenmii, Monlana, Au^u.^t 3, 191(i; Laurel, Montana, 

 July 15. 



The Bozenian specimen is deposited in the collection of The 

 American Entomoloj^ical Society. 



Helina nigribasis sp. n. 



MdU. — Black, subopaque, denselj^ gray pniinescent. Head with dense 

 silvery jn-uinescence on orbits, face and cheeks; antennae and palpi black. 

 Thorax with four black dorsal vittae. Abdomen with base of first tergite 

 black, the other tergites each with a pair of black spots, those on fourth 

 sometimes indistinct. Legs black, apices of all femora and all of tibiae 

 reddish testaceous. Wings slightly brownish; cross-veins very sHghtly 

 infuscated. Calyptrae white. Halteres yellow. 



Eyes almost nude, separated at narrowest part of frons by a distance 

 about equal to width across posterior ocelli; interfrontalia almost obliter- 

 ated just in front of ocelli; orbits bristled over midway to anterior ocellus; 

 jiarafacial in profile nearly as wide as third antennal joint, narrowed below; 

 cheek one-fourth as high as eye; longest hairs on arista nearly as long as 

 width of third antennal joint. Presutural acrostichal bristles absent or 

 very small; prealar minute or absent; three pairs of postsutural; dorso-centrals 

 present; sternopleurals 2:2, the lower anterior one weak; hypopleura bare; 

 scutellum without ventral or lateral hairs. Abdomen subcylindrical; basal 

 sternite bare; fifth sternite with a deep central cleft, the surface with a number 

 of stout, moderately long bristles on each side of cleft. Fore tibia with or 

 without a weak median posterior bristle; mid and hind femora each with a 

 few long bristles on basal half of postero-ventral surface, the latter with a 

 complete series on antero-ventral surface; mid tibia with three or four pos- 

 terior bristles; hind tibia with one or two antero-ventral, three or four antero- 

 dorsal, and three or four postero-dorsal bristles, all short. Third vein bare 

 at base; veins three and four divergent at apices. 



Female. — Differs from the male in having the basal abdominal tergite 

 usually with a pair of dark spots, and the mid and hind femora with their 

 apices broadly rufous. 



Frons over one-third of the head-width at vertex, slightly wider anteriorly. 

 Fore tibia usually with one or two posterior bristles; mid tibia with an antero- 

 dorsal bristle at or near middle. In other respects as male. Length, 5.5 to 

 6.5 nun. 



Type.-~c^; Dongola Illinois, May 12, 1917. Allotype.— 9 ; 

 topotypical. Pamtypcs. — Dongola, Illinois, May 9, 10 and 12, 

 1917, and May 12, 1916; Dul^ois, Illinois, May 24, 1917; Carlin- 

 ville, Illinois, May 18, (C. Roliertson). Thirty-nine specimens. 



Type and paratypes in collection of Illinois Natural History 

 Survey, paratypes also are deposited in the collection of The 

 American Entomological Society. 



TR.\NS. AM. ENT. SOC, XLVI. 



