May, 1920] Descriptions of Diptera 269 



Type, allotype, and two paratypes, Savonoski, Naknek 

 Lake, Alaska, July, 1919. 



Mydaea hirtiventris sp. n. 



Male. Black, shining, with bluish gray pruinescence on thorax and 

 abdomen. Antennas and palpi black. Thorax with four black vittae. 

 Abdomen unmarked. Legs black, hind tibice brownish. Wings clear, 

 bases yellow. Calyptras and halteres yellow. 



Eyes separated by a little more than width across posterior ocelli; 

 orbits setulose to anterior ocellus; interfrontalia distinct on its entire 

 length; eyes nearly bare; parafacial as wide as third antennal segment, 

 not narrowed below; cheek nearly twice as high as width of parafacial; 

 arista with its longest hairs a little longer than its basal width; third 

 antennal segment over twice as long as second. Prealar a little over 

 one-third as long as the bristle behind it; stemopleurals 1:2. Basal 

 steniite with numerous hairs. Fore tibia with the postero ventral hairs 

 longer than usual; mid femur with strong bristles to beyond middle of 

 posteroventral surface; mid tibia with two or three posterior bristles; 

 hind femur with rather short, closely placed bristles on entire length of 

 antero ventral surface, and some weaker bristles on basal half of postero- 

 ventral: hind tibia with two or three anteroventral and anterodorsal 

 bristles, the setulae on apical half of anterior surface stronger than usual. 



Length, 7 mm. 



Type, Katmai, Alaska, 1917. One male. 



Hebecnema pallipes sp. n. 



Male. Shining black, head with browmish pruinescence, thorax 

 with faint grayish pruinescence, which is only visible when the surface 

 is viewed from an angle of 45 degrees, abdomen densely brownish 

 pruinescent, with a slight coppery tint, and without any markings. 

 Legs yellowish testaceous, coxae and tarsi fuscous. Wings slightly 

 smoky. Calyptras and halteres yellow. 



Eyes bare, separated b}^ not more than the width of anterior ocellus, 

 the facets on upper surface much enlarged; parafacial linear; cheek a 

 little higher than width of third antennal segment; longest hairs on 

 arista about as long as width of third antennal segment. Chaetotaxy of 

 thorax as in timbratica Fallen. Fifth stemite with a very deep, U-shaped 

 posterior excision, the lateral extensions bare apically. Fore tibia with- 

 out median or apical posterior bristles; mid femur with several bristles 

 on basal half of posteroventral surface; mid tibia with two posterior 

 bristles; hind femur with four or five bristles on apical half of antero- 

 ventral bristles. Outer cross-vein straight; inner cross-vein before 

 apex of first vein; last section of fourth vein about 1.75 as long as 

 preceding section. 



Length, 5 mm. 



Type, Katmai, Alaska, 1917. One male. 



