* OSTEN SACKEN ON WESTERN DIPTERA. 235 



the cross- veins at the base of the third and fourth posterior cells are 

 verj' distinct here, while in E. dodrans there is a hardly perceptible in- 

 fuscation ou the cross-vein at the base of the fourth cell only. In E. 

 dodrans^ the distance between the bases of the third and fourth jjoste- 

 rior cells is a little greater than in E. titubans; finally, in the latter, the 

 antennal style is comparatively longer. 



Eab. — Colorado Springs (P. R. Uhler)^ two specimens (somewhat 

 rubbed off ou the abdomen). One of them has, on both wings, an adven- 

 titious stump of a vein inside of the discal cell. 



11. ExoPROSOPA DORIS n. sp. — Base of the wings as far as the basal 

 cross-veins brownish ; costal cell yellowish ; first basal cell, except its 

 proximal end, which is pale yellow, and first posterior cell, except its 

 distal end, brown ;' the middle portion of the marginal and first sub- 

 marginal cells brown, which thus forms an incomplete, irregular, and 

 ill-defined cross-band, expanded anteriorly as far as the end of the first 

 vein, attenuated posteriorly, and ending in the brown of the first pos- 

 terior cell ; the distal boundary of this cross-band is in zigzag, one of the 

 projections touching the proximal end of the second submarginal cell ; 

 the iDroximal boundary is evanescent; a round, brown spot on the prox- 

 imal end of the second posterior cell; an irregular, ill-defined, narrow, 

 oblique, brown band runs from the small cross- vein across the discal cell, 

 covers the proximal end of the third posterior cell and the posterior 

 cross-vein, cuts in two the anal cell, and ends in the axillary without 

 touching the posterior margin ; small clouds on the bifurcation of the 

 second and third veins and on the proximal end of the discal cell. Epis- 

 toma yellow", clothed with yellow scales ; cheeks pale yellow, with a sil- 

 very covering of scales ; front and vertex black, with golden-yellow scales ; 

 posterior orbits silvery; proboscis not projecting beyond the oral mar- 

 gin ; antennre black; first joint short, reddish; the third conical, with 

 a style half as long as the joint. Thorax with yellow pile; white pile 

 above the root of the wings and in front of the reddish scutellum ; sil- 

 very-white pile on the chest and pleurae ; abdomen densely clothed with 

 yellow scales, except at the base of the second and on the fourth seg- 

 ments, where there are cross-bands of white scales ; seventh segment 

 likewise beset with white scales ; venter reddish-yellow, with snow-white 

 scales on the first four segments and yellowish scales on the following 

 segments, with an admixture of black ones on the fifth segment. Fe- 

 mora red, clothed with fulvous scales ; tibite reddish, darker on their 

 front side; the front pair black at tip; the hind pair is black, thickly 

 clothed on the inner side with fulvous scales ; tarsi black. Halteres with 

 a yellow knob. Length 7-8"™. 



Bab. — Humboldt Station, Central Pacific Railroad, Xevada (July 29). 

 A single very well preserved specimen. 



A second specimen, from Oregon (H. Edwards), is considerably larger 

 (from 12""" to lo'"™); the coloring of the body is exactly the same; the 

 distribution of the brown spots on the wings is, in the main, the same, but 

 4 H B 



