214 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



especially in the foot-hills of the Sierra Nevada ; the same species occurs 

 in Colorado. From the high Sierra I brought three Tabani and two 

 Chrysops. Besides these species, I describe a Chrysops commou in the 

 Colorado region and Utah. For comparison's sake, I will state that at 

 least sixty species of Tabanus and twenty-five Chrysops occur east of 

 the Mississippi. None of these species has as yet been found in Cali- 

 fornia. Dr. Philippics essay on the fauna of Chili enumerates twenty- 

 two Pangonice (including Mycteromyia), thirty-five Tabani, but only two 

 (Jhrysops. The occurrence of Silvias in the western region is remarka- 

 ble, as it is one of the numerous points of analogy between its fauna 

 and that of Europe. A Silvius isabellinas, said to be from the Atlantic 

 States, has been described by Wiedemann, but it has never been found 

 since, and if it exists it must be a very rare species. In Central 

 Europe, a single Silvius occurs 5 another one is an alpine species of 

 apparently local occurrence, described by Mr. Loew. 



Chrysops fulvaster, from Colorado and Utah, has a fenestrate spot in 

 the discal cell, like several European species, mostly belonging to the 

 Mediterranean fauna. Not a single one of the twenty-five Chrysops 

 from the Atlantic States has this peculiarity. 



Chrysops noctifer, from the Sierra Nevada, seems to resemble most 

 closely two species from Lapland, one of which, according to Dr. Loew, 

 also occurs in Sitka. 



Pangonia. 



Pangonia hera n. sp. — Proboscis short, hardly projecting beyond the 

 palpi ; body uniformly blackish- gray ; wings grayish-brown ; eyes pubes- 

 cent, first posterior cell open. Length 13-14 mm . 



Female- — Antennae black; two basal joints grayish ; face and front 

 dull yellowish-gray, the former with pale yellowish-white hairs, the lat- 

 ter (at least in my specimen) with a black, shining, denuded space in 

 the middle ; the proboscis hardly reaches beyond the short and stout 

 gray palpi ; lips large, developed ; eyes pubescent, in life unicolorous, 

 green 5 ocelli distinct. The black ground-color of the thorax and of the 

 abdomen is partly concealed under a dust-colored, dingy-gray pollen; 

 both are clothed with pale yellowish-white hairs. Wings tinged with a 

 dingy brownish-gray ; some lighter shades are visible in an oblique light, 

 especially along the rounded part of the hind border and in the second 

 basal cell ; first posterior cell open ; a long stump of a vein at the base 

 of the fork of the third vein. 



Sab. — San Francisco, Cal., caught in the street twice, by Mr. Henry 

 Edwards, in July. I have a single female. 



Pangonia incisa (syn. Pangonia incisuralis Say, Journ. Acad. Phila., 

 iii, p. 31 ; Amer. Ent., plate xxxiv ; Pangonia incisa Wiedemann, Auss, 

 Zw., i, p. 90). — Colorado Springs, Colo., in August (P. E. Uhler); Arkan- 

 sas (Say). The descriptions are easily recognizable. 



