NORTH AMEEICAN DIPTERA. 293 



pile whitish. Abdomen like the dorsum of the thorax ; at the base, witli yellowish 

 pile, beyond with a short, reclining, sparse black hairs; a narrow band at the 

 base of the second segment, gray polliuose, beyond it a broader brown band; 

 ovipositor directed backward, composed of five segments, their entire length 

 about equal to that of the two preceding segments together, forming a tapering 

 continuation of the abdomen, the last one elongate, reddish, and split nearly to 

 its base. Legs light yellow, the tip of four anterior tarsi, the tip of hiud femora 

 and the rest of the hind legs reddi.sh. 



The thorax, abdomen and wing-neuration are like those of Trich- 

 ophthahnia A^ovm HoUangce Macquart, as figured in pL ii, fig. 7, Dipt. 

 Exot. ii, 1. The last segment of the ovipositor is not as long. I de- 

 scribed the eyes as bare, but, by looking across the under part with a 

 good lens, a few scattering hairs are visible, and it is possible that in 

 the male they may be more distinctly pubescent. This is the fourth 

 species of this family now recorded from North of Mexico, viz., 

 Hirmoneura {Parasymmiclm) clausa O. S., H. flavipes, Rhynchoceph- 

 alm /Sackenii Will., and B. volaticus Will. In my description of the 

 last species I should have described the "black" pile of the abdomen 

 as dark chocolate-brown, and the " white" tomentum as glistening- 

 light yellow. 



THEREVID^ 



There va v talis O. Sacken, Western Dipt. 274. 



I have several specimens of this species from Washington Terri- 

 tory. In some the blackish bristles of the vertex and front are want- 

 ing ; in others the pile of the thoracic dorsum is in large part black. 

 A female with them, and which seems to be of the same sj^ecies, dif- 

 fers in having the pollen above more brownish, and is as usual less 

 pilose ; it is most especially characterized, however, by the presence 

 of two large, round, deep velvet-black spots on the front 



Tliereva crassicoriiis n. sp. 



Jl/(//e.— Black, white pollinose and pilose; the thickened first antenual joint 

 thickly black hairy above; vertex and thoracic dorsum black pilose; front bare; 

 wings hyaline, stigma and narrow clouds of the discal veins brown. Length 

 9-10 mm. 



Eyes separated only by a sutural space, front bare of pile. Antennae black, the 

 first joint pollinose, above with long black hair and bristles, below with black 

 .bristles and white (jile. Head below densely white pilose and with sparse 

 black hairs ; occipito-orbital bristly hairs black. Dorsum of thorax in the middle 

 with three slender pollinose stripes, enclosing two opaque dark ones; on the 

 sides blackish and pollinose; pile black. Pleurpe thickly white pollinose and 

 pilose. Abdomen thickly wdiite pollinose and with recumbent, moderately long, 

 white pile. Femora black, white pilose, tibite luteous yellow, their tip black ; 



