DIPTEKA— SYRPHIDJ5. 559 



half, and even here show no neuration at all beyond the general course of 

 the principal veins at the very base; the alula?, however, are very distinct, 

 very large, their breadth (along the wing) fully equal to half the breadth 

 of the thorax, dark, with obliquely transverse dark ridges, indicating that 

 they were wrinkled in nature, much as in Volucella or CEstrus. Abdomen 

 long, broadest in the middle of the basal half, beyond tapering considerably, 

 the tip roundly pointed; apical half of basal joint black, forming a distinct 

 transverse straight band; the number of abdominal joints appears to be five. 



Length of thorax, 3.5™'"; breadth of same, 3.25'"'" ; length of abdomen, 

 6.5"""; wings, 12""'; breadth of same, 3.5""". 



Dr. Williston thinks it can not be an Eristalis. 



Chagrin Valley, White River, Colorado. One specimen (W. Denton). 



SYRPHUS Fabricius. 

 Syrphus sp. 



Syrphus sp. Scudd., Bull U. S. Geol. Geogr. Siirv. Terr., IV, 755 (1878). 



A species of this family, and in size second only to the Milesia from the 

 same beds, is represented by reverse and obverse of a single specimen, 

 which is too imperfect for description, only the body being preserved ; the 

 form and size of this agree best with the genus Syrphus. 



The length of the body is lO'""'. 



Grreen River, Wyoming. One specimen, Nos. 4110 and 4132 (S. H. 

 kscudder). 



CHILOSIA Meigen. 



Chilosia ampla. 



PI. 9, Figs. 14, 27. 

 Cheilosia ampla Scndd., Bull. U. S. Geol. Gaogr. Surv. Terr., IV, 753-754 (1878). 



This species is primarily founded on a single specimen which Mr. 

 Bowditch and I found in the shales at Green River, and which preserves 

 nearly all parts of the insect. There is also a specimen with its reverse 

 which we obtained at the same place, and another which Mr. Richardson 

 sent me from these beds, agreeing with the first-mentioned specimen, but a 

 little larger. As only the bodies are preserved, they are temporarily placed 



