190 U. S. NATIONAL MUSEUM BULLETIN 216 



ivory; propodeum black, usually more or less ferruginous in pleural 

 areas and medially; legs ivory, the hind coxa fulvous or pale brown 

 posterobasally and anterobasally, and the hind tibia with a fuscous 

 front and back stripe extending from a subbasal spot to the apex; 

 abdomen blackish. 



Female: Color like that of the female of Exochus russeus, except that 

 first lateral area of propodeum and basal 0.3 of combined basal area and 

 areola are black, and that the abdomen is brown with the apical part 

 of the tergites rufescent, more broadly so laterally and on the median 

 tergites. 



Type: cf, Oak Creek Canyon, Ariz., May 20, 1947, H. and M. 

 Townes (Washington, USNM 63648). 



Paratypes: 9d\ Oak Creek Canyon, Ariz., May 17 to 20, 1947, 

 H. and M. Townes (Townes). 5cf, Parker Creek, Sierra Ancha, 

 Ariz., Apr. 20 to May 4, 1947, H. and M. Townes (Townes). 5d\ 

 Workman Creek, Sierra Ancha, Ariz., May 3 and 6, 1947, H. and M. 

 Townes (Townes). 29, campus of University of Colorado, Boulder, 

 Colo., T. D. A. Cockerell (Washington), d", 9, Spearfish, S. Dak., 

 July 25 and 26, 1924 (Washington and Townes). 



This species has been taken in South Dakota, Colorado, and Ari- 

 zona. In Arizona we found it in mid-spring, among the herbage of 

 moist stream bottoms at altitudes of about 5,000 to 6,000 ft. 



IV. GRAVIPES GROUP 



Front wing 4.2 to 6.5 mm. long; head rather narrow, with long 

 sloping temple; face rather narrow, very strongly convex transversely, 

 rather strongly and evenly convex in profile, its interantennal process 

 triangular with an apical angle of about 60 degrees; frons below ocelli 

 with a broadly triangular weakly raised area, of which the median 

 ventral angle is rather prominent; cheek rather long, about 0.6 as 

 long as basal width of mandible; base of mandible unusually broad 

 but be3 7 ond the base soon tapered to normal width; occipital carina 

 absent or present laterally as a very fine carina; clypeal margin 

 weakly convex or medially straight; head black, usually with inter- 

 antennal process and small spot at top of eye pale, sometimes with 

 face and clypeus largely or entirely pale yellow; notaulus present as 

 a sharp pit or a somewhat impressed ovoid area next to mesoscutal 

 margin; metapleurum with none to very many discal hairs; costula 

 present; second lateral area of propodeum usually with hairs only 

 in its apicolateral part, but sometimes with hairs everywhere except 

 basomesally; apical transverse carina of propodeum complete; nervu- 

 lus opposite basal vein or beyond it by not more than 0.28 of its 

 length; front spur of middle tibia about 0.85 as long as hind spur; 

 second segment of middle tarsus about 1.7 as long as wide; first 



