ZooL.— Vol. II.] WHEELER— DOLICHOPODIDM. 23 



yellowish cast and light yellow veins. Venation normal; tips of the third and 

 fourth veins close together; distal segment of fifth vein scarcely longer than 

 the posterior cross-vein. Halteres and tegulae white, the latter with pale 

 cilia. 



One specimen from Avalon, N. J. (July 22d), received 

 from Professor J. M. Aldrich. 



In the concavity of the front, structure of the antennae, 

 shape of thorax and general coloration, this species departs 

 from Medeterus and resembles our smaller species of Psil- 

 ofus. The neuration, however, is unmistakably that of a 

 typical Medeterus. 



23. Medeterus maurus, sp. no v. 

 Plate II, Fig. 46. 



Male. Length 3.25-3.5 mm.; length of wing 3.5 mm. Proboscis and 

 palpi black. Face deep metallic blue, with a cross-band of gray dust just 

 above the suture. Antennae short, yellow; third joint black, except at the 

 base, pilose, broader than long, rounded, with a slight indentation near its 

 middle for the insertion of the slender, naked arista. Postocular cilia white. 

 Front, thorax, scutellum and abdomen black, shining with a faint metallic 

 blue reflection, most pronounced on the abdomen. Thorax and scutellum 

 covered with thin white dust, the latter with four prominent black bris- 

 tles; the former with numerous small black bristles on its anterior third and 

 moderately long black bristles on the posterolateral portions. The short 

 hairs on the abdominal segments are black in some lights, yellowish in 

 others. Hypopygium slender, as long as the abdomen, shining black. The 

 two pairs of appendages at its tip are rather short, translucent and yellowish. 

 Coxae and legs black, the knees, middle tibiae and bases of the middle tarsi 

 yellowish. Hairs on the anterior surfaces of the coxae and the bristles above 

 the insertions of the fore coxae, black. Hind metatarsus plain, about half as 

 long as the succeeding joint. Wings clear, iridescent, with yellow veins, 

 growing whitish towards their bases. Venation normal; distal segment of 

 fifth vein one and one-half times as long as the posterior cross-vein. Hal- 

 teres and tegulae white, the latter with white cilia. 



Female. Length 4 mm.; length of wing 4 mm. Proboscis large, swollen, 

 glabrous, black, with conspicuous yellow hairs. Face somewhat broader, 

 and its deep metallic blue ground-color more distinct than in the male. The 

 abdomen is considerably flattened dorsoventrally, the slender brown ovi- 

 positor exserted and covered with a few slender hairs. Legs and coxae 

 black throughout, excepting the knees which are light yellow. 



Two males and two females from Mt. Washington 

 (J. M. Aldrich). 



