psilopus. 235 



reasons I have no doubt that this is the genuine female of P. dif- 

 ftcsus. The specimens of my collection show that the difference in 

 the extent of the black coloring on the fore margin of the wings in 

 both sexes is not always so considerable as the pair in Winthem's 

 collection shows it. If then, in accordance with the foregoing, the 

 easily recognizable male of P. diffusus is to be stricken out from the 

 list of North American species, I will nevertheless insert here a more 

 accurate description of this species, which has been only insuffi- 

 ciently characterized by Wiedemann. 



P. diffusus Wied. % and 9. — Viridis, nitidissimus, fasciis nigri- 

 cantibus alarum duabus, valde difflueutibus, antice conjunctis et pos- 

 tice abbreviatis, facie nuda, pedibus nigris, tibiis tarsisque anticorum 

 testaceis, setis tibiarum anteriorum perlongis, halteribus nigris. 



^..Duobus ultimis tarsorum intermediorum articulis postice candido- 

 pilosis, appendicibus hypopygii majusculis, fuscis. 



9 . Tibiis tarsisque intermediis piceis. 



Green, very shining ; both blackish bands of the wings very diffused, but 

 united in front, abbreviated behind ; face without hairs ; feet black, 

 tibiae and tarsi of the fore feet brownish-yellow ; bristles of the four an- 

 terior tibise very long ; halteres black. 



£ . The two last joints of the middle tarsi with snow-white hairs on the 

 posterior side ; the rather long appendages of the hypopygium blackish- 

 brown. 



9. Middle tibia? and middle tarsi pitch-brown. Long. corp. 0.22 — 0.23. 

 Long. al. 0.24—0.25. . 



Syx. Psilopus diffusus Wied., Auss. Zweifl. II, 221, 17. 



Metallic-green, bright, shining. The lower part of the face, 

 the posterior corners of the thorax and the scutellum (in one of 

 the males) steel-blue. The very much excavated front beset, be- 

 sides the usual black bristles, in the male with longer, in the 

 female with somewhat shorter and more sparse hairs, which are, 

 on the middle of tire front of a whitish, on the sides of a more 

 blackish, in the male even of an almost black color. The rather 

 broad face is glabrous and only very sparsely dusted, its lower 

 part rather distinctly separated from the upper part and the latter 

 rather convex. Antennae black, rather small, the second joint 

 with rather long black bristles ; the arista is of more than middling 

 length, and has a subapical position. Palpi black, with numerous 

 black hairs ; proboscis brown-black. The bristles of the thorax 

 and the four bristles of the scutellum are black, and rather lon«\ 

 Pleurae with white dust. The green color of the abdomen changes 



