ART. 9 TWO- WINGED FLIES OF TRIBE MILTOGRAMMINI ALLEN 41 



tral bristles present; scutclhim with three nearly equal pairs of mar- 

 ginals. Abdomen densely gray pollinose, the intermediate segments 

 when viewed from the rear each with three large, vaguely defined, 

 triangular black spots. In the female, sclerites which appear 

 to be the fourth, fifth, and sixth sternites but which are very likely 

 part of the genitalia, together with the lower valve of the genitalia, 

 cause a conspicuous bulge in the lower, posterior part of the abdomen. 

 Wings hyaline ; apical cell closed or narrowly open at margin of wing ; 

 hind cross-vein not parallel to section of fourth vein beyond the bend. 

 Legs black, rather short and stout; middle tibia with one bristle on 

 outer front side near middle. 



Length 4.0 to 5.0 ram. 



Type.— Male, Cat. No. 3634, U.S.N.M. 



Host relationsJiip. Unknown. 



Bange. — New York, Virginia, Indiana, Illinois, Colorado, Arizona, 

 California, British Columbia. 



The following material has been examined: The type, which is a 

 male from southern Illinois (Robertson), and a female from Santa 

 Clara county, California (Baker) , of the type series; two from Colorado 

 (Coquillett), two from Lafayette, Ind. (J. M. Aldrich) ; and other 

 specimens from Kaslo, British Columbia (R. P. Currie) ; Oswego, 

 New York; Tuscon, Arizona (J. M. Aldrich); all in the collection 

 of the National Museum. Two females from Falls Church, Virginia 

 in the collection of Mr. Nathan Banks. 



Genus OPSIDIA Coquillett 



Opsidia Coquillett, Journ. New York Ent. Soc, vol. 3, p. 102, 1895; 

 Proc. U. S. Nat. Mus., vol. 37, p. 580, 1910. Genotype, 0. gonioides 

 Coquillett, Atlantic City, N. J. — Adams, in Williston's North American 

 Diptera, p. 376, fig. 151, No. 90, 1908. — Townsend, Smithsonian Misc. 

 Colls., vol. 41, p. 64, 1908. 



In Coquillett 's description of the genus, only a single male was 

 available, and some of the characters given can scarcely be considered 

 more than specific. The outstanding characters of the genus based 

 on the genotype, and a new species, 0. metopioides, are as follows: 



Front with a single frontal row of bristles on either side ol the 

 vitta, which extend downward to slightly below base of antennae; 

 proclinate ocellars present; orbital bristles in both sexes. The facial 

 depression deep and narrow with parallel sides, is the most distinc- 

 tive character of the genus. Facial ridges with bristly hairs not 

 extending above the lowest fourth; vibrissae differentiated, and 

 inserted far above front edge of oral margin; antennae extending 

 nearly to vibrissae; arista with penultimate joint less than twice as 

 long as wide; in profile, head length at vibrissae much less than at 

 base of antennae; bucca and back of head black setulose, without 

 pale hairs about the oral cavity; proboscis slender, at most slightly 



54292— 2Gt 4 



