84 J. M. ALDRICH. 



obovate lamellje black, as large as the three antenna! joints together, with a very 

 small white portion at the base : cilia of the lateral and inferior orbit white. 

 Thorax and abdomen bronze-green, somewhat ohs(uired in jiarts by greenish white 

 pollen; the groove above the root of the wing velvet-black; second and third 

 segments of the abdomen, with the central part of the hypopyginm, having a 

 coppery luster; tegular cilia black ; lower part of the pleurje with thin golden 

 pollen, which becomes thicker near the coxae and extends down the outside of 

 the middle ones; fore coxae and legs yellow, the former with a golden luster; the 

 fore feet compressed, a little infuscated, with a satiny white reflection ; on the 

 outer side of the femora the hairs are fine and long and curly ; the fore tibiae are 

 a little enlarged beyond their base and have two rows of slender bristles, those in 

 the postero-lateral row are slightly flattened ; posterior femora and tibiae yellow, 

 the latter tipped with black; middle tarsi a little pale at base, the rest black, 

 hind ones black ; middle femora with conspicuous long hairs before along the 

 lower part; the same but in a less degree on the hind femora; lamellae of the 

 hypopygium whitish, small, with only small hairs. Wings short, moderately 

 narrow, gray, yellowish at base. 



Female. — Face whitish, wider, antennae very short, third joint but slightly in- 

 fuscated ; fore tibiae infuscated towards the tip. Legs with ordinary, but rather 

 long bristles, two preapical bristles on hind femora (as in the male also), body 

 color a little darker than in the male. Length 4.7 mm. ; of wing 3.2 mm. 



One male, two females, Moscow, Idaho, June 18. On moist sand 

 at edge of mountain brook. 



Macellocerus moeclius Loew, Neue Beitraege, viii, 40 ; Mon. Dolicho- 

 podidfe., 110 {Tachytrechm) . Trenton Falls, N. Y 



I have one male, Algonquin, 111. (Dr. Nason , and one female, 

 Franconia, N. H. (Mrs. Slosson). 



Macellocerus sailUS Osteu Sacken, " Western Diptera," 316 (Tachytrechus) . 

 California. 



I have numerous specimens, Craig's Mountain, Nez Perces County, 

 Idaho, June 22 and 26, and Moscow, Idaho, June 18 and 25. Most 

 of these were collected on fallen logs about the edges of a little damp 

 meadow ; others were taken at the edge of mountain streams- on 

 moist sand. 



