OSTEN SACKEN ON WESTERN DIPTERA. 3 LI 



the few hairs on the vertex and on the upper part of the occiput yellow- 

 ish-white ; those on the lower part of the occiput pure white ; antennae, 

 black. Thorax with two, rather distant, brown stripes, expanded and 

 somewhat diverging anteriorly ; the hairs and spines on the thoracic 

 dorsum are whitish ; scutellum with a quantity of long, erect, whitish 

 hairs on its edge ; a semicircular impressed line parallel to this edge 

 is very distinct. Abdominal segments 2-6 at the base each with a pair 

 of semicircular brown spots, gradually diminishing in size on each sub- 

 sequent segment; a vestige of such spots is also visible on the seventh 

 segment. Hypopygium of the male black, beset with whitish pile and 

 with an appressed tuft of yellow hairs above the forceps. In the female, 

 the eighth segment is black, shining. Legs yellowish-gray, with short, 

 appressed, whitish pile and yellowish-white bristlesc Wings with a 

 slight brownish tinge; small cross-vein before the middle of the discal 

 eell ; second posterior cell sometimes very narrow, in some specimens 

 even petiolate ; the fourth posterior, in some specimens, coarctate to- 

 ward the end, even closed ; these characters are very inconstant. 



Hab. — San Francisco, Oal., on the sands about Lone Mountain, April 

 6, and again June 29. Four males and four females. 



Nicocles. 



(Jaennicke, formerly Pygostolus, Loew, Centur., vii, 28.) 



Of the two Californian species described by Dr. Loew, I have found 

 (only N. dives, at the Geysers, Sonoma County, in the first days of May. 

 j Mr. James Behrens had taken it a few days before near Mendocino. 



Family DOLICHOPODID^E. 



The first insect of this family which I found after my arrival in Cali- 

 fornia was a Hydrophones (Santa Barbara, January 28). Since then, 

 until the middle of May, I did not come across a single Dolichopodid, 

 although both the fauna and flora of the environs of San Francisco 

 attain their fullest development from the end of March to about the 

 middle of May, when the effect of the cessation of the rain begins to 

 be visible. Among the exuberant insect life of that season I did not 

 discover a single Dolichopus in sweeping the grass with my net, nor did 

 I see a single Psilopus or Ghrysotus running on the leaves of low shrubs 

 (in Florida I used to catch them abundantly in such situations as early 

 as March). May 14, I caught a Hygroceleuthus and a Dolichopus, one 

 specimen of each, on the walls of the railroad station at San Rafael. 

 Since then, in June and July, 1 found a few Dolichopodidce along the 

 streams of running water in Sonoma County. 



All in all, I brought home, from Marin and Sonoma Counties, two 



Hygroceleuthus, one Dolichopus, two Tachytrechus, one Liancalus, and my 



t new genus Polymedon ; one Psilopus from Yosemite Valley j from the 



i High Sierra, two Dolichopus, one Tachytrechus, one Scellus, one Hydro- 



