24 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



24. Medeterus viduus, sp. nov. 



Plate II, Fig. 39. 



Male. Length 4 mm.; length of wing 3.5 mm. Proboscis, palpi and face 

 subopaque, black, the last with a transverse band of gray dust just above the 

 suture. Antennae yellow, tip of second joint and whole of third joint, black, 

 the latter about as long as wide, pubescent, with slender subapical arista. 

 Front opaque with gray dust. Cheeks glabrous, black. Postocular cilia pale 

 yellow. Thorax opaque with brown dust on the anterior half, with gray dust 

 on the posterior half covering the prescutellar depression . Two distinct gray 

 stripes, bordering the outer edges of the rows of acrostichal bristles, traverse 

 the anterior half of the thorax and become confluent with the gray of the 

 prescutellar depression, as do also two shorter lateral gray streaks just above 

 and in front of the insertions of the wings. Humeral bristles rather sparse 

 and short, and, Hke the moderately developed dorsal bristles, black. Scu- 

 tellum covered with gray dust, with four well developed black bristles. 

 Abdomen shining bronze-black, the segments covered with hairs which are 

 black in some lights, grayish in others. On either side of the seventh seg- 

 ment there is a prominent tuft of long black hairs. Hypopygium long and 

 slender, of the same color as the abdomen, appendages slender, with yellow- 

 ish tips. On the lower (morphologically dorsal) surface of the organ the hairs 

 are conspicuously long. Pleurae and coxae black, subopaque with gray dust. 

 Bristles above the fore coxae and hairs on the anterior surfaces of the fore 

 and middle coxae, black. Legs black, knees narrowly and indistinctly yel- 

 lowish. Hind tibia bearing some conspicuously long yellow hairs near its 

 tip on the upper side. Hind metatarsus a little more than half as long as 

 the succeeding joint. Wings hyaline with black veins, becoming somewhat 

 lighter at their bases. Venation normal. Tips of third and fourth veins 

 close together. Distal segment of fifth vein one and a half times as long as 

 the posterior cross-vein. Halteres and tegulae flesh-colored, the latter with 

 white cilia. 



A single male from Olympia, Washington (J, M. Aldrich). 



The peculiar yellow hairs on the tips of the hind tibiae 

 will serve to distinguish this species from the other North 

 American forms. 



25. Medeterus Aldrichii, sp. nov. 



Male. Length 3.5 mm.; length of wing 4 mm. Proboscis very large, 

 swollen, laterally compressed, glabrous, black, with yellow hairs. Palpi glab- 

 rous, black. Face below the suture shining deep metallic blue, just above 

 the suture dusted with gray. Below the insertions of the antennae the ground 

 color of the face is more greenish blue. Basal joint of antennae yellow, sec- 

 ond and third joints black, the latter as long as broad, rounded, pubescent, 

 with slender, naked subapical arista. Front opaque, with brown dust in the 

 middle, with gray dust along the orbit and on the occiput. Postocular cilia 



