AMERICAN DIPTERA. 221 



purer yellow color, tarsi generally markedly annulate; middle tibia? with a 

 trace of an infuscation at tip. The middle tibise are nearly the length of the 

 femora. Sciitellar bristles shorter, especially the lateral ones. Anal angle of 

 wing less prominent, anal vein stronger, and anal cross-vein more oblique. The 

 rest of the neuration is the same. 



Seven specimens; Dubois (7200 feet altitude), and Hunter's 

 Creek, Wyoming, September 6-10, 1895 (Wm. M. Wheeler) : 

 Oxford, Idaho (J. M. Aldrieh). 



Platypalpus incnrTus sp. nov. {Figs. 31, 33, 44). 

 Length 2-2.5 mm. Head, thorax and abdomen black. Proboscis short, black ; 

 palpi white to piceous. Antennae elongate, black, third joint lanceolate, arista its 

 equal. Face narrow, white to whitish. Vertex and thoracic dorsum with green - 

 brown dust merging to slaty below and on abdomen. Upper portion of occiput 

 with black bristles, lower with white ones; thorax with black bristles. Halteres 

 yellow. Basal half of each abdominal segment with a coating of slaty dust, 

 outer half shining. Hypopygium terminal or flexed to the right, small to mod- 

 erately large, with a fringe of yellow hairs on left side. Legs light yellow ; tarsi 

 slightly dusky, a little darker at tip of each joint, sometimes almost annulate: 

 legs slender, front femora but little thickened, a little larger than front tibiw. 

 which are enlarged and slightly compressed. Wings clear, nerves weak to brown ; 

 second basal a little the longer, anal vein generally moderately strong, sometimes 

 the third vein is parallel with the costa, sometimes both the third and fourth are 

 reflexed at the tip, meeting the wing margin beyond the apex of the wing. 



Twenty specimens, the males predominating; Los Angeles Co. 

 and San Diego Co., California, December and February. 



It seems quite probable that this species is in a state of division. 

 As a general rule the smaller hypopygium, weak venation, straightei- 

 third vein and light-colored palpi are correlated, but this is not uni- 

 versally true. 



PiatypalpiiN gravidiis sp. nov. (Figs. 2.5, 42j. 

 Black, except legs, wings and halteres. Face grayish, moderately narrow. 

 Palpi dusky red ; proboscis a little shorter than head. Third anteunal joint 

 lanceolate, in length equal to its arista. Thoracic bristles black. Abdomen 

 shining, with sparse whitish hairs; hypopygium not large. Pleura slaty, with 

 usual plaga. Legs yellow-testaceous, front coxse more or less black at base, other 

 coxae varying from yellow to black ; all the tarsi largely, evenly, dusky to pice- 

 ous; front femora moderately, middle more strongly, hind not, incrassate; spur 

 of middle tibiae moderate, black at tip. Wings with browish tinge, veins fuscous 

 strong; third vein straight, except extreme tip. first posterior cell a little wider 

 in the middle, narrower just before apex, second basal cell longer than the first, 

 its outer vein oblique, anal cell open behind. Average length 2.5 mm. 



Sixteen males, thirty females; San Diego Co., California, Febru- 

 ary and March. 



TRANS. AM. ENT. SOC, XXVIII. JULY, 1902. 



