90 



^ Croi i 



one-third times as long as the second, arista thickened on the basal 

 half, the penultimate joint scarcely longer than wide; thorax thinly 

 gray pollinose, marked with four bhick vitta', three postsutural and 

 three sternopleural macrocha'ta^, scutellum bearing four niarginal pairs, 

 abdomen thinly gray ]>()llinose on the last three segments, which bear 

 marginal macroclueta^ ; front tarsi noticeably dilated; middle tibia> 

 each bearing three or more macrocjha'ta' on the front side near the 

 mid<lle, hind tibin' not ciliate outwardly; wings hyaline, the base yel- 

 low, third vein bearing three or four bristles near the base, bend of 

 fourth vein angular and bearing a stump about as long as the small 

 crossvein, the vein beyond it strongly arcuate, hind crossvein near last 

 fourth of distance from the small to the bend; calyiiteres white ; length, 

 9 mm. Colorado. Two female specimens collected by Mr. Carl F.Baker. 

 Ty])e No. 3587, IT. S. National Museum genalis n. sp. 



Genus EXORISTOIDES, new genus. 



The characters of this genus, of which johnsoni is the type species, 

 may be gleaned from the table of genera on preceding pages of this 

 work and from the descrii)tion of this si>ecies given below: 

 Third joint ot antenna' concave on the iroiit edge, three or lour 

 sternopleural nnujrocha'tje, apex of scutellum and of abdomen 

 black; black, the palpi, and sometimes the base of the third 

 antennal joint, j^ellow; front in male three-fourths as wide as, in 

 the female slightly wider than, either eye, two pairs of (u-bital 

 bristles in the female, wanting in the male, frontal bristles 

 descending to the arista, cheeks one-fourth as Avide as the eye 

 height, vibrissa^ on a line with front edge of oral margin, two or 

 three bristles above each, antennre almost as long as the face, 

 the third joint in the male five, in the female two and one-third, 

 times as long as ,the second, arista thickened on the basal two- 

 fifths to three-fifths, the penultimate joint slightly longer than 

 broad; thorax gray pollinose, marked with four black vitta', 

 three postsutural macrochu'ta', scutellum bearing three long 

 marginal pairs and a short apical pair; abdomen thinly gray 

 I)ollinose and with reficcting darker spots, last three segments 

 bearing discal and marginal macrocha'ta'; niiddh^ tibia' bearing 

 three or more on the front side of each near the middle, front tarsi 

 of female greatly dilated, front i)ulvilli of male almost as long 

 as the last tarsal joint; wings hyaline, first vein bearing two or 

 more bristles on the outer half, third vein bristly almost to the 

 small crossvein, bend of fourth vein almost rectangular, desti- 

 tute of an appendage, vein beyond the bend strongly arcuate, 

 hind crossvein nearly stiji.ight, slightly beyond middle between 

 the small and the bend; ('alyi)teres white; length, (! to 7 mm. 

 Easti)ort, Me.; Franconia, N. II.; Westville and Clenu^nton, 

 N. J. Three males and three females, collected May 30 and July 



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