OSTEN SACKEN ON WESTERN DIPTERA. 223 



4. Chrysops surdus n. sp. — Female. — Very like C. proclivis, but dif- 

 fers in being smaller; the facial callosities are black and shining on both 

 sides of the dividing furrow; being prolonged anteriorly, they coalesce 

 above the mouth ; the ferruginous space between them is a narrow stripe, 

 interrupted anteriorly. The thoracic dorsum anteriorly shows two dis- 

 tinct gray longitudinal lines, reaching to about the middle of the thorax ; 

 the pile on the pleura is of a paler yellow. On abdominal segments 1 and 

 2, the elongated black square is more distinctly coarctate on the hind 

 margin of the first segment ; on segment 3 there is a yellow dividing line 

 in the middle, but the lateral yellow marks in most cases do not exist. 

 The prevailing color of all the legs is black, with only a little reddish 

 at the base of the four posterior tibise and tarsi. The design on the 

 wings does not show any important difference. Length 7-8 mm . 



Rab. — Webber Lake, Sierra County, California, July 21. Four 

 females. 



The eyes of this species have the normal coloration (like the figure 1 

 in my Prodrome). 



Family LEPTID^E. 



As far as the small number of known Leptidce from California enables 

 me to judge, this family exhibits, on the Pacific slope, a more European 

 than Eastern American character. 



The striking forms. of golden-haired Chrysopilce, the principal feature 

 of the fauna of the Atlantic States, are replaced here by small and in- 

 significant species. 



The genus Triptotricha, however, hitherto peculiar to North America, 

 seems equally well represented in the Atlantic and Pacific States. 



The considerable number of Californian species of Symplwromyia and 

 the abundance of specimens are remarkable. 



Triptotricha lauta Loew, Centur., x, 15.— California. 



Triptotricha discolor Loew, Berl. Ent. Zeitschr., 1871, p. 379.— 

 California. 



I have neither of these species. A specimen which I found near Lake 

 Tahoe, Sierra Nevada, July 19, seems to be different from both. 



Leptis costata Loew, Centur., ii, 4. — Not rare in Marin and Sonoma 

 Counties, California. The front and hind legs of my five specimens are 

 not as dark as described; but the coloring of the legs seems to be very 

 variable. 



Leptis incisa Loew, Centur., x, 16.— The female alone is described; 

 the male has usually much darker femora ; the coloring of these, how- 

 ever, is very variable in both sexes. One of my females has a pale red- 

 dish scutellum ; another has it black at base, reddish toward the tip. 

 Not rare in Marin County in April. 



Chrysopila humilis Loew, Berl. Ent. Zeitschr., 1874, p. 379.— 

 Male. — "Atra, opaca, tota pilis lutescentibus vestita; tibise testaceae, 



