58 BULLETIN 31, UNITED STATES NATIONAL MUSEUM. 



cheeks iu front more sbiuiug. Face somewhat receding in profile, the 

 tubercle inconspicuous; cheeks convex below. Antennae brownish 

 black. Frontal triangle pollinose, with black pile. Abdomen opaque 

 black; the first and fifth segments and the hypopygium shining green- 

 ish black; second segment with a small rounded spot on each side; third 

 segment with a large quadrate spot iu front reaching to a little beyond 

 the middle; fourlh segment similar, the spots scarcely reaching beyond 

 the middle; fifth segment shining, wholly without yellow. Front legs 

 yellow, tbe tibiae gradually and nearly evenly dilated from the base to 

 the tip, the external angle below not produced, metatarsi moderately 

 dilated, thence gradually narrowed to the tip; middle legs yellow, 

 blackish toward the base; hind legs black, the tij) of femora, the base 

 and tip of tibiic, tip of metatarsi and the second and thirds joints, yel- 

 low, AVings nearly hyaline; stigma dilutely yellow. 



$ . Like the male but the abdominal spots smaller, sometimes want- 

 ing on the second segment, the fifth segment also with a pair of spots; 

 the legs with less black, and the fore legs not dilated. The front and 

 middle legf^ are wholly yellow, and the black on the hind legs confined 

 to a ring on the femora and tibiie and with the metatarsi blackened. 



Six males and one female from Colorado, four females and one male 

 from the White Mountains, New Hampshire, July 25-30, and one female 

 from Pennsylvania (Keen). 



This species is closely allied to P. chwtopodus, but differs in the male 

 in the front femora not having the row of conspicuous bristly black 

 hairs on the outer side and in the spots on the fifth abdominal segment 

 being wanting ; in both sexes by the spot on the second segment being 

 small, rounded, or subtriangular. 



Platychirus peltatus. (Plate III, tigs. 11, 11a.) 



Si/ri)hu!i peltatus Meigen, Syst. Beschr., iii, 334. 



Scceva albimana Fallen, Syrph., 46, 19. 



SciBva pellata Zetterstedt, Dipt. Scand., ii, 747; viii, 414.5, 50. 



riaUicheiru8 peltains Stager, Kroj. Tijdschr., iv, 320; Schiner, Dipt. Austr., i, 295. 



Habitat — Northern Europe, White Mountains, Pennsylvania, New 

 York!, Sitka (Lw.). 



$ ,9 . Length, 8 to 9™™. Metallic shining green. Antennae blackish 

 brown, the third joint somewhat lighter or yellowish below. Face 

 thickly covered with yellowish dust, leaving the tubercle and cheeks 

 in front more shining ; in profile, concave below the antennae, with a 

 prominent tubercle and a smaller one below it, near the oral margin. 

 Frontal triangle bronze colored, but little shining, the pile black ; front 

 with a slight coppery or bronze reflection ; dusted on the sides below, 

 dilated in the middle so that there is only a narrow shining space be- 

 tween the two. Thorax bright, shining, metallic green. Abdomen iu 

 the male opaque black, shining metallic green on the first, tip of fourth, 

 the fifth, and the sixth segments ; in the female wholly moderately shin- 

 ing. Second segment with a moderately large yellow spot on each side, 



