AMERICAN DIPTERA. 223 



may be equally developed or very slight. Abdomen convex, 

 broad, of nearly equal length throughout, very bare, not- 

 withstanding the very short hair and short bristles ; the latter 

 located on the middle of the segments near the lateral mar- 

 gins, very evident on the proximal segments, more obscure 

 on the successive ones. Male hypopygium apparently on the 

 sixth segment, sometimes hidden, with a lateral slender, 

 curved process, and a median, stouter, likewise curved organ. 

 In the female only six abdominal segments are present intact ; 

 the seventh and eighth being short and withdrawn into the 

 sixth. Legs rather stout, the femora with bristles near the 

 apex on the upper side ; all the metatarsi jagged on the middle 

 of the underside. Marginal cell of wing widely open, the sec- 

 ond vein terminates in the costa a considerable distance beyond 

 the confluence of the first vein by a well marked curve; the 

 veins at the outer ends of the discal and fourth posterior cell 

 sometimes, more often not, parallel, though nearly so, and 

 not in same straight line; first posterior cell side open, the 

 fourth posterior closed some distance from the margin, the 

 anal cell closed. 



Type. — Psilocurus nudiusculus Loew. 



Psilocurus is very closely related to Laphystia. The chief 

 differences between them lie in the possession by the former 

 of two or more stout bristles on the scutellar margin which are 

 absent in Laphystia, and in the structure of the antennae; in 

 Psilocurus the third segment is rounded, oval, and the style 

 is entirely rudimentary, while in Laphystia it is elongate conical 

 and its style is very stout, but not at all rudimentary, and 

 plainly two-jointed. The much broader protuberant face and 

 broader front of Laphystia are other helps in separation. 



SYNOPSIS OF SPECIES. 



1. Legs and antennae wholly black (S. Da.) nioclestus. 



Legs and first segment of antennae reddish-yellow; the femora 

 with a broad black fasciae above (Southwestern species). 



nudiusculus. 

 Psilocurus iiiodestus. 



Orthoneuromyia modestus Williston, Kans. Univ. Quart., II, 67, 

 1893. 

 "(j^- — Length 7-8 mm. — Black throughout, the pulvilli and halteres 



TRANS. AM. ENT. SOC, XXXV. • JUNE, 1909. 



