153 



DIPTERA OF NORTH AMERICA. 



triangle, blackish-cinereous. Antennae entirely black. Face yel- 

 lowish, orbits narrow, whitish. Thorax above with very narrow 

 almost obsolete lines. Abdomen a little darker and less opaque 

 than the thorax, last segment black, smooth. Legs blackish, 

 knees and tip of the anterior tibiae yellowish, hind tibiae either alto- 

 gether blackish, or marked with a narrow, very obsolete pale ring, 

 tarsi yellowish, their last joints blackish. Halteres impure white, 

 knob somewhat darker. Wings cinereo-hyaline, with clearer 

 spaces round the infuscated transverse veins, second costal seg- 

 ment almost twice as long as the third. 



Hob. Pennsylvania. (Osten-Sacken.) 



Observation. — This species is very like PMlygr. femorata Stenh., 

 but distinguished by entirely black antenna?, by a less obtuse an- 

 terior angle of the ocellar triangle and by a conspicuously longer 

 second costal segment. 



III. EPHYDRINA. 



The Ephydrina are well characterized by their quite naked, prom- 

 inent, and usually much rounded eyes, by the second joint of their 

 antennae not unguiculated, and by the middle tibiae without spinous 

 bristles on their upper side. By the genus Pelina they are nearest 

 related to the latter genera of Hydrellina. The mentum is much 

 enlarged and swollen in almost all the genera, the oral cavity 

 generally of large width. The genera with less widely opened 

 mouth, as Pelina and Ochthera, so manifestly bear the chief cha- 

 racters of Ephydrina, that no doubt can arise about their systema- 

 tic position. 



The genera of Ephydrina hitherto established may be arranged 

 as follows : — 



Division 1. Clypeus prominent. 

 , ( The small basal cells of the wings complete. 



The small basal cells of the wings wanting. 

 2 ( Oral cavity proportionally narrow. 



I Oral cavity exceedingly wide. 

 o ( Fore femora not thickened. 

 ( Fore femora much thickened. 

 Costal vein attaining the third longitudinal vein. 

 4 ■{ Brachydeutera Loew. 



Costal vein attaining the fourth longitudinal vein. 5 



Canace Hal. 

 2 

 3 

 4 

 Pelina Hal. 

 Ochthera Latr. 



