AKT. 17. FLIES OF THE GENUS TACHYTRECHUS GREENE. 11 



rounded. Arista about twice the length of the head; lamellae 

 rounded at tip, tapering down to a point at the base, and below this 

 is a snow-white area nearly as long as the lamella ; stem black, very 

 slender and slightly thickened at extreme base. Thorax and scutel- 

 lum very dark green with brown dustlike reflections in certain lights ; 

 scutellum dark green. Abdomen brighter green in certain lights, 

 blackish along apical edge and very broadly silvery-white pollinose 

 on basal three- fourths. Hypopygium large, yellowish at base, whit- 

 ish in center and blue green on apical third, the edge and projecting 

 parts reddish-black and heavily chitinous; lamella yellow, some- 

 what triangular in shape, fringe brown. Femora, tibiae, and basal 

 three- fourths of middle metatarsi yellow, rest of middle tarsus and 

 all of hind tarsus brownish; front tarsi all yellow with silvery 

 pruinosity, but in certain lights it is slightly infuscated above with 

 brown. Front tibia has a row of black macrochaetae on the front 

 and side; between these two rows is a row of fine, short, bristly 

 hairs, and two or three large macrochaetae near the base. Wings 

 very faintly tinged with brown on apical half; tegulae whitish yel- 

 low with long black fringe; halteres yellow; stems slightly brownish 



on base. 



Female.— Vevy much like the male, except the following points: 

 Face immediately below the antennae nearly as broad as the lower 

 part, heavily coated with silvery dust, slightly shorter than the length 

 of eye. Antennae little darker, third joint nearly all black, reddish 

 along lower basal edge. Arista normal, about as long as face. Legs 

 deep brown, except apical third of all femora and basal half of all 

 tibiae reddish yellow ; all femora with a deep greenish reflection. 



Length, 4^-5 mm. 



Tyjm locality.— Nev^Y^ort, Oregon, August 12, 1902 ; J. M. Aldrich, 



collector. 



Described from two males and eight females. 



Type, mole.— Allotype, female and three paratypes. Cat. No. 

 24133, U.S.N.M. 



Allied to T. sanus, but is easily separated by the difference of the 

 antennae, arista, hypopygium, and the bristles of the front tibia. In 

 sanus the middle row of bristly hairs are longer and the two or three 

 macrochaetae at the base are absent. 



9. TACHYTRECHUS LATICRUS Van Dnzee.^ 



Figs. 15, 17. 

 Tachytrechus laticrus Van Duzee, Ent. News, 1918, p. 46. 

 Male.— Face as long as the eye height, golden yellow, dull, just 

 below the antennae about one-third as wide as the lower part. Front 



'This species was first Identified by D. W. Coquillett, but the description was never 

 published. 



