DIPTEEA— SYRPHID^. 561 



Chilosia ? sp. 

 PI. 9, Fig. 2G, 



Another species resembling the last, but too large to be referred to it 

 and too imperfect to be sufficient for characterization, occurs in the same 

 beds. It is pretty plainly one of the Syrphidas from its general appearance 

 and from such remains of the neuration as are preserved. The abdomen is 

 almost round, considerably surpassed by the wings, and consists of four 

 visible segments, of which the second is conspicuous for its ornamenta- 

 tion, the margins being dark and joined by a blackish mesial longitudinal 

 stripe, next which, on either side, the surface is much paler than elsewhere. 



The length of the body is 7.1°"°; the apparent length of the wings, 

 6.75™"° ; the breadth of the abdomen, 3°"°. 



Green River, Wyoming. One specimen. No. 17 (Dr. A. S. Packard). 



Chilosia sp. 



PI, 9, Fig. 8. 



Cheilosia sp. Scudd., Bull. U. S. Geol. Geogr. Surv. Terr., IV, 754 (1878). 



Two specimens of a smaller species of Syrphidre, preserving the 

 bodies, agree so completely with C. ampla, excepting in their much smaller 

 size, that they are referred to the same genus ; but as the wings are almost 

 entirely lost the reference is made only to indicate the approximate place 

 of the species, which need not be described until better material is at hand. 



The length of the body is 4.25'"°'. 



Green River, Wyoming. Two specimens, Nos. 4113, 4150 (S. H. 

 Scudder). 



PSILOTA Meigen. 



PSILOTA TABIDOSA. 

 PI. 9, Fig. 9. 



A headless body of a testaceous color with a nearly complete wing 

 represents this species. Unfortunately it is not accurately drawn on the 

 plate, the nearly invisible veins connecting the third and fourth longitud- 

 inal veins at their tips and closing the discal cell being omitted and the 

 cross-vein being placed much too near the base. In reality it should lie 

 scarcely within the middle of the discal cell, and the fourth longitudinal 

 VOL xin 36 



