112 S. A. ROHWER. 



a spot within, and tarsi creamy-yellow; basal joints of the flagellum 

 testaceous beneath. Entire insect covered with silvery pile. Wings 

 hyaline, the apex slightly dusky, iridescent; venation black. 



The paratypes have the first recurrent nervures nearer in 

 one case, almost interstitial with the first tran. cu. 



Habitat. — Boulder, Colorado, August 5 and 1, 190S, and 

 July 24, 1908 (S. A. Rohwer). Caught flying over dry, hot 

 sand on a warm day. 



Very close to N. inermis (Cress.), but distinguished by the 

 characters given above. 



Niteliopsis vierecki n. sp. 



Female. — Length 4.5 mm. Clypeus with a broad low middle pro- 

 duction; middle carina rather sharp. Head opaque, finely granular; 

 frontal carinas strong, starting on the inner orbits at about the level 

 of the posterior ocelli, following the orbits downward some way then 

 turning in abruptly, then turning inward and uniting a little above the 

 antennas (they enclose two U-shaped areas, the upper one wide and 

 not entirely closed at the bottom). Ocelli in a little more than an 

 equilateral triangle; a shallow, indistinct furrow extending above and 

 below the anterior ocellus. Antennas slender, third and fourth joints 

 subequal. Prothorax rather narrow, not carinated anteriorly, notched 

 in the middle. Dorsulum finely punctured or granular; scutellum 

 similarly sculptured, not impressed. Metanotum granular without a 

 triangluar area, with a longitudinal carina; metapleurae granular, pos- 

 teriorly finely striato-granular; posterior face with a deep oval-shaped 

 fovea. Radial cell with a faint appendiculation; first recurrent nervure 

 a little basad of the first tran. cu.; second recurrent nervure received 

 beyond the middle of the second cubital cell; tran. med. beyond basal. 

 Abdomen dullish, finely punctured; pygidial area poorly defined. Color 

 black; mandibles testaceous; tegulae, brownish; two spots on pro- 

 notum, tubercles in part, four anterior femora, all the tibias beneath 

 creamy; tarsi brownish; abdomen red. Entire insect, but more es- 

 pecially the thorax with silvery pile. Wings hyaline, apex slightly 

 dusky, iridescent; venation brown, weaking apically. 



Male. — Length 4 mm. The male does not differ much from the 

 female. The antennal joints are shorter, and the third joint is hairy 

 beneath. 



Habitat. — Boulder, Colorado, July 24, 1908 and August 4, 

 and 5, 1908 (S. A. Rohwer). Caught while flying over hot, 

 dry sand in the same locality as N. lucidus. 



Very distinct. Named in honor of Mr. H. L. Viereck, in 

 recognition of his work on American Hymenoptera. 



