AMERICAN DIPTERA. 233 



ing to the oral margin, dividing the face from the cheeks ; proboscis 

 very short, thick and flat; palpi small, broad ; occiput with a row 

 of bristles ; ocelli much reduced ; antennae very short, two-jointed, 

 the outer joint small, oval, its terminal style nearly twice the length 

 of the antenna and slender, but thickened at the very base. 

 Thorax rounded, devoid of acro^tichals, but with two lateral rows of 

 widely separated bristles ; scutellum with two long slender bristles 

 and four minute marginal hairs. Abdomen slender, depressed in 

 the female, and compressed in the male ; hypopygium small, termi- 

 nal but reflected and of less diameter than the abdomen ; female 

 abdomen blunt and compressed at the tip. Legs very slender, 

 nowhere thickened, the front coxse twice as long as the others, and 

 two -thirds as long as their femora; front femora with short spines 

 below, on outer portion no tibial spurs; claws slender, long, empo- 

 dium well developed, longer than the pulvilli. Wings slender, the 

 third vein simple, discal cell rather long, emitting three simple veins 

 to the margin, the second posterior cell narrow at its base, second 

 basal and anal cells short, their outer boundary continuous, oblique, 

 the anal vein thin and short beyond the cross-vein, anal angle 

 poorly developed. 



o ~ 'Oreotlialia pelops sp. uov. 



Length/8 mm. Wholly black, sparsely coated with fine, dull green pollen. 

 Occipital 'and thoracic bristles black, abdominal and pedal hairs pale. Halteres 

 black. Hypopygium twisted to the right, elongate, the central filament superior, 

 directed horizontally forward, lamellse small. Empodia and pulvilli white. 

 Wings infumated, stigraal spot faintly darker, veins dark brown, costal setu la- 

 very minute. 



Numerous specimens of both sexes. Kendrick, Idaho (J. M. 



Aldrich). 



HElflERODROVIIA Meigen. 



Rather small, slender, lengthened species, of yellow, gray or black 

 color. Antennse with three joints, third oyal, pointed, arista short, 

 terminal. Proboscis shorter than the head, curved slightly back- 

 wards. Eyes of both sexes not contiguous. Thorax lengthened. 

 Abdomen longer than the thorax, hypopygium larger than the 

 abdomen. Legs long and slender, the fore coxae much lengthened, 

 equalling or nearly equalling the thickened fore femora. Foi'e 

 femora and tibiae usually with minute spines beneath. Wings long 

 and narrow, the third and fourth veins forked, discal cell with two 

 veins, anal angle not well developed. 



TRANS. AM. ENT. SOC, XXVIII. (30) JULY, 1902. 



