OSTEN SAC REN ON WESTERN DIPTEKA. 231 



20 (15). Proximal half of the marginal cell hyaline : 



21 (21).. Proximal half of the first posterior cell brownish; its latter por- 



tion hyaline: 



22 (23). Cross-veins at the base of posterior cells 1, 3, and 1 clouded with 



brown I 11 - <*°™n. Sp . 



I 12. agassizi Lw. 



23 (22). Cross-veins, etc., not clouded. 13. bifurca Lw. 



21 (21). Proximal half of the first posterior cell hyaline, followed by a 



dark brown space and then again hyaline.. 14. eremita n. sp. 

 . 1. Exoprosopa fasciata Macquart, Dipt. Exot, ii, 1, p. 51, 38; 

 tab. xvii, f. 6.—E. longirostris Macquart, Dipt. Exot., suppl., 4, p. 108, 

 probably, and Mulio americana v. d. Wulp certainly, are synonyms of 

 this species. I also suspect that E. rubiginosa Macq. is nothing but a 

 rubbed-off specimen of this species. E. sordida Loew, Centur., viii, 21, 

 differs in having the anterior part of the wings darker brown, the pos- 

 terior less infuscated ; the base of the third and fourth posterior cells 

 , is strongly infuscated. As the habitat is Matamoras, Tamaulipas, it 

 will probably occur in Texas. 



2. Exoprosopa sima n. sp., 2 .—Very like E. fasciata, but differs in 

 having a shorter proboscis, which does not project beyond the oral mar- 



|gin, or projects very little; the whole body is more blackish ; antennas 

 ; deep black ; relation of the third joint to its style like 4:1; base of second 

 'and the fourth abdominal segments beset with a white, scale-like, 

 i appressed tomentum, forming cross-bands ; the sides of the third segment 

 and the whole seventh have a similar tomentum ; the pile on the sixth 

 (segment slightly yellowish ; legs black ; the pile on the thorax anteriorly, 

 |on the pleurae, and above the root of the wings is pale yellowish-white 

 (Or whitish-yellow, rather than fulvous ; wings like those of E. fasciata 

 Ibut of a more blackish-brown rather than reddish-brown color. Length 

 14-15 mm . 



Hal). — Humboldt Station, Central Pacific Eailroad, Nevada. Three 

 jspecimens, which I caught fiying in the hot sunshine on the top of an 

 arid hill (July 29). 



3. Exoprosopa gazophylax Loew, Centur., viii, 18. — California. 

 I do not know this species, which will be easily distinguishable by its 

 four submarginal cells. 



4. Exoprosopa decora Loew, Centur., viii, 19. — Illinois, Iow T a, 

 Wisconsin, Colorado plains, Georgia. 



5. Exoprosopa dorcadion n. sp. — The coloration of the wings is 

 nearly the same as in E. caliptera. The principal difference consists in 

 the second hyaline cross-band stopping short at the second vein, instead 

 of reaching the first ; the interval between these two veins is filled out 

 with brown, thus connecting the two brown cross-bands, which are 

 bifid posteriorly ; the hyaline spot, which in E. caliptera exists in the 

 marginal cell above the inner end of the second submarginal, in most 

 3ases, does not exist here ; the triangular hyaline spot near the base of 



