294 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



black, with white pile ; tibiae red, with white pile and black and white 

 bristles ; the middle tibise, on the front side, before the middle, are orna- 

 mented with a conspicuous tuft of black bristles, projecting on each 

 side ; hind tibise with a brownish ring a little before the middle. Wings 

 feebly tinged with yellowish-brown on the proximal two-thirds, the rest 

 hyaline; fourth posterior cell coarctate; anal cell slightly open. 



Rab. — Foot-hills of Mariposa County, on the road to Clark's Ranch, 

 beginning of June. A single male. 



Cyrtopogon. 



The large number of species of this genus occurring in California is 

 very remarkable. While only ten or eleven species are known from the 

 whole of Europe, I found thirteen species, eleven of which were new, 

 almost all on the same day, near Webber Lake, Sierra Nevada. Another 

 remarkable fact is the peculiar sexual ornamentation of some of these 

 species, especially of the legs of the male, which, as far as I am aware, 

 does not occur in Europe. One of the species so ornamented occurs in 

 the Rocky Mountains. 



The structural characters of these numerous species (several of which 

 I left undescribed for want of good specimens) offer a great variety, and 

 will facilitate a subdivision of the genus. The synoptical table I give 

 is a very imperfect attempt at such a grouping. The two last species, 

 C. cerussatus and G. nebulo, especially the latter, are only provisionally 

 placed in the genus, for want of a better place. In using the analytical 

 table which follows, attention should be paid to the sex of the specimen, 

 as some of the species were described in one sex only. 



Synoptical table of the species. 



I. Scutellum rather convex above, its posterior edge rounded ; sur- 



face black, sometimes pollinose at the base only, and 

 beset with long pile; legs densely pilose, and rather 

 stout (except in C, princeps, where they are more slen- 

 der) : 

 A. Hind tibia3 more or less reddish in the middle : 



(a) Front tarsi ornamented in the male with dense silvery 

 pile ; middle tarsi with disks of black bristles : 

 1. callipedilus $ 9 ; 2. cymbalista $ 9 ; 3. plausor $ 9 . 

 (aa) Front and middle tarsi not ornamented as above : 

 4. montanus $ 9 ; 5. leucozonus 9 ; 6. aurifex $ 9 . 

 AA. All the tibise entirely black : 



7. princeps $ ; 8. cretaceus 9 ; 9. longimanus $ 9 . 



II. Scutellum more or less flattened above; surface densely grayish- 



pollinose; legs moderately hairy, and not very stout 

 (rather hairy in 0. rattus) : 



