CII11YSOTUS. 177 



covered with brown-gray dust ; the very small palpi black. The 

 third joint of the antennae comparatively with long hair, rather 

 large, oblique, its upper margin much more arched than the lower 

 margin, which is almost straight ; the arista is subapical. Front 

 metallic-green, without a distinct trace of dust and becoming 

 broader upwards. Thorax shining green, sometimes rather gold- 

 green. Coxa? and femora black with metallic-green lustre; on the 

 four anterior feet the extreme tip of the femora, the tibia3 and 

 the greater part of the first joint of the tarsi are yellow, the fol- 

 lowing part of the tarsi black-brown ; the hind tibia? and hind 

 tarsi are decidedly of a brown-black color. The hair upon the 

 feet, though somewhat rough, is short, and even on the hind tibice 

 of very moderate length ; the hind femora have on the under side 

 before the tip but a few bristle-like hairs ; the bristles on the tibise 

 are very scarce ; the pulvilli are very small even on the fore tarsi. 

 Cilia of the tegulae black, though some of them exhibit in a re- 

 flected light a yellow-brownish glitter. Wings somewhat tinged 

 with gray ; veins black ; the posterior transverse vein very close 

 to the root of the wing ; the last segment of the fourth longitu- 

 dinal vein parallel to the third and ending a little before the tip 

 of the wing. 



Female. Face of moderate breadth with grayish-white dust 

 upon rather black ground ; the usual transverse swelling is far 

 below its middle. Palpi blackish, the third joint of the antennas 

 smaller than that of males, and its oblique form' less striking. 

 The brownish-yellow dust on the upper side of the thorax some- 

 what more dense than in males. The color of the four anterior 

 feet like that of the males ; the hind tibiae yellow with a somewhat 

 dusky tip ; hind tarsi dark In-own, the first joint is sometimes more 

 yellowish-brown near the basis. Wings like those of the male, 

 only the anal angle somewhat more protruding. 



Hob. New York. (Osten-Sacken.) 



'Observation. I have no ground for doubting that these two 

 sexes belong together, as all those characters which distinguish 

 the male from the female are within the range of the sexual dis- 

 tinctions peculiar to this genus, and the agreement of all the other 

 characters is very striking. 



12 



