214 A. L. MELANDER. 



length equals the third joint. Vertex shining, sides of face nearly parallel ; occi- 

 put a little pruinose. Dorsum of thorax, pleujse and abdomen very shining, 

 black; notum devoid of bristles or hairs, though all the specimens may be 

 rubbed; scutellum with two fine, dusky bristles. Hypopygium small, append- 

 ages concealed. Legs, including the coxse, yellow, last joint of tarsi black ; legs 

 slender, tibiae spurless, no bristles, except the small setulse on the under side of 

 the middle femora — as in Platypalpus. Halteres small, whitish. Wings clear 

 hyaline, veins light fuscous, not thick ; first basal very little longer than the sec- 

 ond, almost its equal in length ; third and fourth longitudinals straight, parallel 

 on outer portion ; no trace of an anal cell; anal angle not prominent, rounded. 



Eight males and oue female ; Colorado, C. F. Baker. 

 The structure of the middle legs is very much like that of certain 

 Platypalpus. 



PL.ATYPAL.PUS Macquart. 



Rather small flies, the largest species measuring but 4 mm. Body 

 generally black, with yellowish legs. Wings not spotted. Antennae 

 apparently two-jointed, with a terminal arista. Proboscis shorter than 

 the head. Eyes of both sexes separated on the vertex. Hypopy- 

 gium not large, forming a rather blunt ending to the abdomen. 

 Front and middle tibiae much thickened, generally with spines be- 

 neath. The middle tibiae ending in a spur. Wings with the third 

 vein unforked, all the cross veins near the middle of the wing, no 

 discal cell, anal cell present, its cross-vein perpendicular to the wing 

 margin, sixth vein abbreviated more or less basally. 



The generic names Platypalpus and Tachydromia are chosen, not 

 because they are believed the correct solution of an entomological 

 controversy, but rather because most of the North American species 

 have been described under them. 



Femora more or less black 2. 



Femora wholly yellow 8. 



2. Front tibise incrassate 3. 



Front tibiae not incrassate 4. 



3. Large species trivialis Loew male. 



Small species paeliyciiemus Loew.^' 



4. All the tibiae black nioiiticola sp. nov. 



Tibiae more or less yellow 5. 



5. Third antennal joint short, oval 6. 



Third antennal joint lengthed, lanceolate pluto sp. nov.,'' 



6. Second basal cell considerably the longer incultns Coquillett. 



First and second basals subequal 7. 



7. Femora with a well-marked black dot; tibiae yellow apicalis Loew. "-^ 



Anterior femora black above, the others black apically ; tibiae black apically 



(Alaska) diversipes Coquillett. 



