DIAPHORUS. 101 



plastic characters as fully as it is necessary when an American 

 species is to be recognized as identical with a European species. 

 Neither can I mention any reliable characters for the distinction 

 of both species. I believe that the examination of a larger num- 

 ber of specimens will establish their identity. 



Observation 2. — I believe I know the female of D. opacus, am 

 however not certain, on account of the smaller length of the first 

 longitudinal vein and the paler coloring of the hind tibia?. The 

 proboscis of this female is remarkably stout and protruding with 

 a flattened tip ; palpi rather large and broad. Face with an 

 almost imperceptible grayish dust, with a distinct transverse swell- 

 ing upon its middle ; front with gray-brown dust and with a trans- 

 verse furrow below its middle ; all the tibiae yellowish-brown, 

 wings tinged with a dusky blackish color, though not so much as 

 in the above -described male, and towards the fore margin not 

 much darker ; the first longitudinal vein reaches about as far as 

 the middle between the extreme root of the wings and the end of 

 the second longitudinal vein. All the rest as in the male. 



Hab. Pennsylvania. 



2. D. mundus Loew. % and $. — Laete viridis, pedibus totis flavis. 



Light metallic green, all the feet yellow. Long. corp. 0.12 — 0.13. Long, 

 al. 0.12—0.13. 



Sy> t . Diaphorus mundus Loew, Neue Beitr. VIII, 57, 2. 



Light metallic green. The face has a blue-green, but little 

 shining, ground color, which is rather concealed by the distinct 

 white dust ; it is somewhat broader in the female and has a dis- 

 tinct transverse swelling. Palpi yellowish-brown, much larger in 

 the female and blackened to a considerable extent towards the 

 basis. Proboscis dusky yellow or yellowish-brown. Antennae 

 brownish-yellow ; the small third joint more infuscated ; the arista 

 almost apical ; the eyes of the male meet completely on the upper 

 part of the front, while they are separated directly above the 

 antennae by a triangular spot of white dust. The front of the 

 female is of entirely uniform breadth, only very little exceeding 

 the breadth of the face, has a blue-green, scarcely a somewhat 

 shining ground color, and is covered with yellowish dust. The 

 cilia of the upper orbit are black and, on account of their brevity, 

 11 



