24 THE CANADIAN ENTOMOLOGIST 



Holotype, d', Platte Canyon, Colorado; July 17, 1915 (Oslar). 



Allotype, 9 , with the type. 



Paratopotype, 9 . 



Differs from A. saxicola O. S. of Eastern North America in 

 the antennal flagellar segments less elongated and paler coloured; 

 head more yellowish, the thorax without stripes, etc. 



Tribe Eriopterini. 

 Genus Ormosia Rondani. 



Ormosia nimbipennis, sp. n. 



Coloration reddish brown; wings dusky gray; cell 1st M2 of 

 the wings open, the outer deflection of Ma lacking; anal veins 

 convergent. 



Male.- — Length 4 mm.; wing 5.8-6 mm. 



Female. — Length 5.4 mm.; wing 6.3 mm. * 



Rostrum dull yellow; palpi brown. Antennae moderately 

 elongate, uniform dark brown throughout. Head brownish gray. 



Mesonotum reddish brown without distinct stripes; interspaces 

 with a dense, yellow pilosity; tuberculate pits remote from the 

 anterior margin of prsescutum and closely approximated, separated 

 from one another by a distance about equal to one-half the diameter 

 of one; pcstnotum with a slight grayish pruinosity. Pleura pale 

 brown with a sparse, gray pruinosity; sternum dull yellow. Halteres 

 pale yellow. Legs with the coxae and trochanters dull yellow; 

 fen:ora dull yellow, only a little darkened apically; tibiae and tarsi 

 dark brown. Wings dusky gray; costal region and the stigma 

 brownish; veins dark brown; wing membrane with abundant, 

 short, appressed, black hairs. Venation: cell 1st M2 open, the 

 outer deflection of Mz being absent; cross-vein r usually a little 

 shorter than the portion of R2 before it; Ri+z about equal to the 

 deflect'on of Fi+b\ petiole of M2 short, less than the basal de- 

 flection of Cm; anal veins convergent. 



Ahdomen dark brown, the hypopygium a little lighter; hypo- 

 pygium with the pleural appendages acicular at their apices, black; 

 a prominent median appendage, rectangular, the base and head 

 slightly expanded, the latter squarely truncated or slightly concave 

 across the tip. 



Habitat. — Northeastern LTnited States. 



