OSTEN SACKEN ON WESTERN DIPTERA. 217 



hind margins of all the segments fringed with yellowish hairs, which 

 also form faint triangles in the middle of the segments ; in very well 

 preserved specimens, faint lateral spots, formed by yellow hairs, on seg- 

 ments 2 and 3, are -perceptible. Venter reddish, blackish at the 

 base and toward the end. Femora blackish- gray, beset with grayish 

 pile ; front tibiae red at base, their distal half and tarsi black ; four 

 j)Osterior tibiae and first joint of tarsi red, beset with black pile, which, 

 on the hind tibiae, forms a distinct fringe. Wings with a faint grayish 

 tinge; costal cell and stigma yellowish-brown; a faint brownish cloud 

 across the central cross-veins; a small cloud on the fork of the third 

 vein ; the latter often appendiculate. 



Hal). — Marin and Sonoma Counties, California, April 27 to May 9, 

 common. Eleven females. 



Not unlike my T. epistates, but easily distinguished by the black 

 antennae, darker thorax, distinct cloud on the fork of the third vein, more 

 conspicuous fringes of yellow hair on abdominal segments, etc. 



3. Tab anus phjenops n. sp. — A Therioplectes of the same group with 

 T. sonomensis. 



Female — Grayish black; sides of the abdomen red ; wings hyaline, no 

 distinct brown cloud on the bifurcation of the third vein; antennae 

 black. Length 13-14 mm . 



Front gray, a little converging; ocellar tubercle distinct; callosity 

 nearly square, with a spindle-shaped prolongation above; antennae black; 

 third joint rather narrow, its upper angle very little projecting; thorax 

 grayish-black, with the usual lines very faintly marked ; the antealar 

 callosit3 T variable, reddish or dark. The black stripe inclosed between 

 the reddish sides of the abdomen is generally rather broad, and some- 

 what expanded at the posterior margins of segments 2 and 3, so as to 

 appear jagged ; the red on the sides of segments 2, 3, and 4 is clothed 

 with a scarce and very minute golden-yellow pubescence, in the shape 

 of faint, oblique spots ; it also forms a fringe on the incisures. 



T. pliwnops is very like T. sonomensis, but it is usually a little 

 smaller, the front is narrower, the bifurcation of the third vein is not 

 clouded ; in most, but not in all, specimens, the red on the sides of the 

 abdomen is less extended, leaving a broader black stripe in the middle, 

 which is expanded at the abdominal incisures, and therefore appears 

 jagged. In shape, the abdomen is more elongated, with more parallel 

 sides. In life, this species is easily distinguished by the color of its 

 eyes, which are of a very bright green, with comparatively narrow pur- 

 ple cross-bands, much narrower than the green intervals between them : 

 no purple in the upper and lower corners of the eye (at least, in the 

 specimens observed). 



Rob. — Webber Lake, Sierra County, California, July27. Four females. 

 Two specimens from Fort Bridger, Wyo., August 4, seem also to belong 

 here. 



