438 THE NORTH AMEBICAN EMPIDJi—COQUILLETT. vol. xvnr. 



Genus PLATYPALPUS, Maequart, 



All examination of the type of Oscinis crass if emoris, Fitcli, now the 

 property of the National Museum, proves that it belongs to Platijpalpus. 

 P. alexipjmSy Walker, is too imperfectly described to admit of giving 

 it a place in the following table. 



ANALYTICAL KEY TO THE SPECIES OF PLATYPALPUS. 



1. Thorax wlioUy black 5 



Thorax Largely or wholly yellowish, femora and tibiiB wholly yellow, third 



anteuual joint short ovate 2 



2. Without a black vitta on the thorax 3 



With such a vitta ; head, middle of scutellum and dorsum of abdomen black, 



apical spur of middle tibia? minute, first and second basal cells sub- 

 equal, front femora scarcely thicker than the hind ones mesogvammus. 



3. Head black 4 



Head and body and all the members except the eyes and antennal arista 



yellow, first basal cell shorter than the second, front femora twice as 

 thick as the hind ones tersus (p. 439). 



4. First basal cell shorter than the second, sixth vein obsolete at base, proboscis 



wholly black, front femora moderately thickened Iwtus. 



First basal cell as long as the second, sixth vein not obsolete at base, proboscis 



yellow basally, front femora not thickened flavirostris. 



5. Femora wholly yellow 6 



Femora yellow, front and hind ones marked with a subapical black dot, front 



femora moderately thickened, third antennal joint short ovate, first 



and second basal cells subequal apkalis. 



Femora largely or wholly black, third antennal joint short ovate, first basal 



cell shorter than the second, front femora slightly thickened 11 



6. Middle femora greatly thickened 7 



Middle femora subequal to the others, legs slender, subeqiaal in size vicarliis. 



7. Tarsi yellow, apex of each joint black 8 



Tarsi, except the first joint, wholly blackish, third antennal joint short 



lanceolate, front femora slightly thickened, first and second basal cells 



equal in length, sixth vein not obsolete at base lateralis. 



Tarsi of front legs of male wholly whitish, thickly white pilose; middle tarsi 

 wholly black, the first joint ovate and on the side ciliate with short 

 black pile ; anal cell complete discifer, 



8. Anal cell open behind 9' 



Anal cell complete, middle femora greatly thickened 10 



9. Middle femora greatly thickened, spurs at tips of middle tibi;e large, front 



femora very thick, third antennal joint lanceolate, first and second 



basal cells subequal in length a'qualis. 



Middle femora moderately thickened, spurs at rips of front tibi;ie medium, first 



two antennal joints yellow crassifemoris, debilis, 



10. Wings brownish ; autenuce, except the tip, yellow (female) discifer. 



Wings grayish hyaline, antenna* wholly black, the third joint short ovate, 



front femora moderately thickened, first basal cell shorter than the 

 second trivialis. 



11. Pleura, excei^t a small spot, wholly opaque, whitish jiollinose, middle femora 



greatly thickened ; inhabits tlio Atlantic States pachijcnemns. 



Pleura wholly shining, destitute of pollen, middle feuiora not thickened; 



inhabits California incidtus (p. 439). 



