200 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



teres yellowish ; abdomen brown ; legs yellow, tips of the femora and 

 of the tibise slightly iufuscated ; male forceps with strong horny black 

 appendages. 



Kab.—>5sin Eafael, Cal., April, May; San Francisco, June. Two males 

 and a female. In one of the males, the cross-veins in the second and 

 third posterior cells are wanting, so that both discal cells are open. 



Eeioptera forcipula Osten Sacken, Monogr., iv, p. 163. — I have a 

 male and two females from San Eafael, Cal., March 31, and Lagunitas 

 Creek, Marin County, April 15, which agree very well with the specimens 

 from the Atlantic States. The male has an uncommonly large forceps, 

 of complicated structure ; on the comparison of the detail of that struct- 

 ure, impossible in dried specimens, would rest the final identification 

 of the species. 



U. forcipula belongs to the subgenus Molophilus. I have two other 

 Californian species of the same subgenus, but only a single specimen of 

 each (San Eafael, March 31 5 Summit Station, Sierra Nevada, July 17). 



(?) Erioptera ursina Osten Sacken, Monogr., iv, p. 164, of the At- 

 lantic States is perhaps identical with the European E. murina. These 

 singular, small, black flies form swarms above running waters in shady 

 places. I have observed the same phenomenon on Lagunitas Creek, 

 Marin County, April 14, but have kept only a single, badly preserved 

 specimen. 



Trimicra pilipes (Fabricius), a European species, the description of 

 which may be found in Schiner, Fauna Austr., Diptera, ii, p. 536 ; a 

 more detailed one in Schummel, Beitr. z, Ent., p. 152 (Limnohia Jimhriata). 

 About the genus Trimicra, established by me, see the Monographs, 

 iv, p. 165, tab. ii, f. 1, wing. — This very common Californian species, 

 occurring everywhere through the winter and spring, I hold to be ident- 

 ical with the European species (I have specimens from Angel Island, 

 January 11; Santa Barbara and Los Angeles in February; San Eafael 

 in April; Santa Cruz in May). The specimens differ very remarkably 

 in size, the largest measuring up to 8"""; the smaller specimens are 

 usually females. In identifying these specimens with the European 

 species, I rely upon the descriptions of the latter and my recollection of 

 them; I have no specimens for comparison. Trimicra anomala O. S. of 

 the Atlantic States is much more rare, and I have never found it as 

 large as the other. ^Nevertheless, I think now that this also is the same 

 species. The specimens which I have- seen from Mexico and South 

 America also resemble Trimicra pilipes very much (compare Monogr., iv? 

 p. 167), and it is not at all improbable that this species, like the follow- 

 ing, its close relative, has a very wide distribution. 



Symplecta punctipennis, common in Europe and in the Atlantic 

 States, occurs in Colorado and is common in California. I have speci- 

 mens from Los Angeles and Santa Monica, taken in February ; from 

 San Eafael, March 31; Lake Tahoe, July 18. I have observed before 

 (Monogr., iv, p. 171) that Idioneura macroptera Pliilippi from Chili is 



