55G TERTIARY INSECTS OF NORTH AMERICA. 



vein, and the third, fourth, and tit'tli longitudinal veins are not united at 

 their extremities by marginal veins ; iiideed, they run without swerving and 

 subparallel to one another to the margin. Tn this respect the genus differs 

 also from other (Jonopida% as it does -also in the extreme length of the third 

 basal cell, which is as long as in Syrphidse. In these points of neuration 

 it would seem to agree better with the Pipunculidas, whicii family, however, 

 is entirely composed of very small flies, so that it seems better with our 

 imperfect knowledge of the fossil to refer it to the Conopidie. The bod\' 

 resembles that of Syrphus in general form. I'he wings are as long as the 

 body and slender, with very straight veins; the auxiliary and first to fourth 

 longitudinal veins are almost perfectly straight, the third originating from 

 the second longitudinal vein at some distance before the middle of the wing; 

 the auxiliary vein terminates beyond the middle of the costal margin; 

 directly beneath its extremity is the small transverse vein, and about mid- 

 way between the latter and the margin the large transverse vein uniting the 

 fourth and fifth veins; the extremity of the second basal cell is farther from 

 the base than the origin of the third longitudinal vein, and the third basal 

 cell reaches very acutely almost to the margin of the wing. 



POLIOMYIA RECTA. 



PL 9, Figs. 19, 21. 



Poliomyia recta Seuild., Bull. U. S. Geol. Geogr. Surv. Terr., IV, 755(1878); in Zittel, Handb. d. 



Pahtout., I, ii, 807, Kig. 107-2 (1885). 



The single specimen referable to this species was obtained at the 

 "Petrified Fish Cut," and represents a dorsal view of the insect with the 

 wings partly overlapping on the back. It is the smaller fly referred to in 

 Dr. Hayden's Sun Pictures of Rocky Mountain Scenery, page 98. The 

 head is broken ; the thorax is stout, rounded ovate, and blackish ; the 

 scutellum large, seini-lunar, and nearly twice as broad as long, with long 

 black bristles along either lateral edge and along the sides of the thorax 

 posteriori)'. The wings are long and narrow ; the auxiliary vein runs into 

 the margin just beyond the middle of the wing; the first longitudinal vein 

 runs into the margin at about two-thirds the distance from the tip of the 

 auxiliary vein to that of the second longitudinal vein, and scarcely turns 

 upward even at the tip ; the straight second and third longitudinal veins 

 diverge from each other at the extreme tip after running almost parallel 



