8 PROCEEDINGS OF THE NATIONAL, MUSEUM. tol. 00. 



dark velvet}?^ brown; ocellar triangle slightly darker, dull brown. 

 First two joints of antennae blackish; first joint when viewed from 

 behind, brownish; when viewed from in front, opaque-black, ex- 

 cept inner projection; about one and one-half times the length of 

 the second; third joint missing. Thorax with the ground color of 

 brilliant metallic copper-color, shining through a thick coating of 

 brown dust ; a broad central stripe shining ; sides with a pale brown 

 and in certain lights with a nearly white pruinosity. Abdomen 

 deep bronze, sides reddish broadly though lightly dusted with a 

 whitish pruinosity. Hypopygium large, black ; stem short and fairly 

 thick; lamellae dull black with longer hairs on the outer edge. Legs 

 mostly bronze blackish with whitish pruinosity ; tips of all tibiae and 

 tarsi black (except base of metatarsi). Tips of all femora, greater 

 part of the tibiae and base of metatarsi faintly reddish yellow. 

 Front coxae half as long as the front femora and about twice as thick 

 as same. Pulvilli relatively longer than in fioridensis, snow-white. 

 Wing with a large black spot at apex, touching the third vein in front 

 and bisected by the fourth; a small, hemispherical, snow-white spot 

 behind at the tip of the wing. Halteres deep brownish yellow on 

 the knobs, base of stem nearly black. 



Female. — Very much like the male except as follows: Wing en- 

 tirely hyaline. General color of body and dark portions of the legs 

 more greenish. Central stripe of thorax not polished, nearly as dull 

 as the sides. Abdomen more greenish and with more white pruinosity. 

 Legs paler yellow, this color more noticeable than the black. 



The male is labeled " 12 m. N. AV. of Lusk, Wyo. July, '95 ; U. of K. 

 Lot 428 ; Type ; W. M. Wheeler, collection." The female labeled the 

 same except Lot 430. Both specimens in the collection of the Ameri- 

 can Museum of Natural History, Mew York City. 



6. TACHYTRECHUS BINODATUS Loew. 



Fig. 14. 



Tachytrechus Unodatus Loew, Centuries, 1S61, pt. 7, No. 84, p. 106. 

 Macellocerns binodatus Loew, Trans. Amer. Ent. Soc, 1896, vol. 23, p. 83. 



Male. — Face about as long as the eye ; dull golden-yellow ; just be- 

 low antennae about half as wide as at lower end. Front bronze green, 

 not very shiny. Ocelli j^ellowish. Antennae mostly bright yellow; 

 first joint swollen at apex, nearly as wide at apex as it is long, black, 

 bristly hairs above; second joint quite small and rudimentary; third 

 joint slightly rounded, mostly brownish-black, a little yellow along 

 the base. Arista mostly black, slightly swollen at base, a lamella in 

 the middle and another at the tip ; the outer half of the stem and the 

 base of the apical lamella white. Orbital cilia black above and whit- 

 ish below. Thorax and scutellum bronze-green covered with a brown 

 dust; two velvety black spots in front of the base of the wings, the 

 anterior spot not very distinct. Abdomen more brassy-green coated 



