AMERICAN DIPTERA. 217 



One male, three females; Omilteme aud Amula in Guerrero, 

 Mexico. Alt. 6000-8000 feet. July, August, September. 



The peculiar variation shown by one specimen may be mentioned 

 again. This individual, apparently the most mature, has the side 

 of the mesonotum and the pleurae luteous, a curious departure from 

 the usual black thorax. This specimen has also the base of the 

 third vein and the underside of the second basal cell very strong. 



Platypalpus pachycneiiius Loew. 



Cent. V, 77. 



Black, shining, dorsum of thorax and scutellum opaque, with cinereous pollen. 

 Antennae fuscous, third joint short, ovate. Coxse light testaceous, darker basally, 

 femora piceous, apex of all and upper side of the posterior pair testaceous, ante- 

 rior and middle tibise fuscous, anterior tibiae incrassate, lighter at base and be- 

 neath, middle tibiae with a large spur, posterior tibiae yellowish, darker at tip; 

 middle tarsi black, posterior tarsi testaceous at base, darker at apex, front tarsi 

 darker at base than at apex. Third longitudinal vein incurved, converging with 

 fourth. 



District of Columbia (Osten Sacken). 



In the shorter diagnosis Dr. Loew mentions that the first basal 

 cell is the longer. This error is corrected in the main description. 



I'latypalpus mouticola sp. nov. (Fig. 41). 



Black, not shining, head and thorax covered with grayish white pollen. Face 

 and front broad, gray pollinose. Antennae black, third joint defective. Palpi 

 black, with gray hairs; proboscis black, two-thirds the height of the head. Tho- 

 racic bristles yellow ; scutellum with two long, yellow, terminal bristles. Abdo- 

 men and hypopygium shining, black. Halteres reddish. Legs firm, but not 

 much thickened, front femora hut little thicker than hind ones, middle femora a 

 little stronger, front tibiae not incrassate, spur of middle tibiae moderately strong. 

 Whole of legs black, except the brownish knees. Wings cinereous-hyaline, veins 

 firm, fuscous, third and fourth parallel, nearly straight; second basal cell the 

 longer, its outer vein oblique; anal vein almost wholly gone. 



Male and female. Length 1.5-2.5 mm. 



Four specimens; Colorado and Cameron Pass, Colorado, July 

 31st; 11,800 feet. 



The only species yet found with black tibise. 



Platypalpus pliito sp. nov. (Fig. 39). 

 Black. Antennae black, third joint lanceolate, lengthened, arista equal to 

 length of the antenna. Face rather narrow, grayish ; front moderately gray- 

 brown pollinose; occiput but little shining. Palpi and proboscis small, black. 

 Thorax moderately shining, gray-brown pollinose on dorsum and gray on pleurae, 

 except usual smooth intercoxal space ; its macrochaetae black ; scutellum with 

 two terminal bristles. Knob of halteres yellowish white, first joint of pedicel 

 infuscated. Abdomen shining; hypopygium shining, not large; last two seg- 



TEANS. AM. ENT. SOC, XXVIII. (28) JULY, 1902. 



