100 



the foartli segment bearing a discal and a marginal row of ma 

 crocba'ta' ; wings hyaline, third vein bearing three bristles near 

 its base, bend of fourth vein not appendiculate, this vein 

 nearly straight after the bend; ealypteres white; length, 

 7 mm. Xortliern 111. A female specimen collected by W. A. 

 Xason. Type jSfo. .')599, U. S. Natioiuil .Museum. . (crata n. sp. 

 Apical cell open, abdomen not tinged with bronze; black, the palpi 

 and inner side of each antenna largely yellow, sides of front 

 bearing only a few short hairs, cheeks one seventh as broad as 

 the eye height, facial ridges bristly on the lowest fifth, third 

 joint of fintennje slightly over twice as long as the second, 

 thorax marked with three black vittte, scutellum bearing two 

 long and an intermediate short pair of marginal macrochietje, 

 abdomen on the last three segments gray poUinose and with 

 numerous reflecting black spots, third vein of wing bearing a 

 single bristle near its base, fourth vein strongly curved inward 

 beyond the bend; length, 4 mm., otherwise as above descrip- 

 tion of (crata. Colorado. A female specimen collected by Carl 

 F. Baker. Type No. 3G00, U. S. National Museum . .parva n. sp. 



24. Middle tibise each bearing a single macrocha'ta on the front side 



near the middle, tbird joint of antenu;e in each sex four times 



as long as the second 25. 



Middle tibijc each bearing two or more macrochicta' on the front 

 side near the middle, scutellum largely yellow, i)ollen of body 

 gray, front in male three-fifths, in the female two- thirds, as wide 

 as either eye, third joint of autennai in the male three and one- 

 half, in the female thiee, times as long as the second; length, 6 

 to 11 mm. Canada; White Mountains, New Hampshire; New 

 Bedford, Mass.; Clementon, N. J.; Maryland; District of Co- 

 lumbia; Virginia,; Dayton, Ohio, and St. Louis, Mo. (Trans. 

 Amer. Ent. Soc, Vol. XIX, p. 287 ; December, 1892. Myxexorista 

 sp.,Brauer and Bergenstamm in litt. Sisyropas])., Brauer and 

 Bergenstamm in Utt.) cudri/w Town. 



25. Scutellum largely yellow; hairs on basal half, of fourth segment of 



abdomen two-thirds as long as the inacrochii^ta% front in the 

 male three-fifths, in the female two-thirds, as wide as either 

 eye, the sides olive gray i)ollinose and bearing numerous 

 nearly erect short hairs; length, (I to 9 mm. District of Colum- 

 bia; Jennings, Va. ; Fort George, Fla.; and Miss. (Biol. Cent.- 

 Amer., Diptera, Vol. II, p. G9; February, 1890. Mi/xcxorista 



sp., Brauer and Bergenstamm in Utt.) Jiavivostris v. d. W. 



Scutellum black ; hairs on basal half of fourth segment of abdo- 

 men one-third as long as the macrocha^ta', front in the male 

 two-thirds, in the female one and one-sixth times, as wide as 

 either eye, the sides silvery gray pollinose, bearing a few very 

 short inconspicuous hairs; black, the second antennal joint, 

 apex of ijroboscis, and the palpi yellow; two pairs of orbital 



