AMERICAN HYMENOPTERA. 121 



rather large punctures scattered over it; line from the anterior ocellus 

 distinct but not complete; ocelli in an equilateral triangle, each 

 ocellus in a small pit; distance between the eyes at the top about 

 equal to the length of the antennal joints 3-4; third and fourth 

 antennal joints equal. Dorsulum, scutellum and mesopleurae shining, 

 with a few large punctures. Metanotum finely granular; metapleurae 

 finely striated. Tarsi with some short, stiff hairs. Abdomen shining, 

 impunctate. Black; mandibles, all the tarsi and anterior tibiae piceous 

 or rufous. Wings slightly yellowish-hyaline; venation brown. 



Habitat.— Florissant, Colorado, June 12, 1908 (S. A. Roh- 

 wer). Flying over warm, dry sand. A female from Boulder, 

 Colorado, August 4, 1908 (S. A. Rohwer) is a trifle larger, the 

 metapleura is more strongly striated, the third cubital is a 

 little narrower on the cubitus, and there is a more or less 

 distinct longitudinal carina on the metanotum. 



Dipoplectron bidentatiformisn. sp. 



Male. — Length 5.6 mm. Somewhat more robust than usual. 

 Anterior margin of the clypeus in the middle produced into a bidentate 

 process (the teeth more widely separated than in D. rufoantennatus) ; 

 at the sides near the eye there is a distinct rather sharp tooth. Front 

 rather strongly, closely punctured; vertex with a few large punctures; 

 no line from the anterior ocellus; ocelli in an acute triangle; distance 

 between the eyes at the top a little less than the length of the antennal 

 joints 3-4. Third antennal joint longer than fourth; apical joint 

 obtusely rounded at the apex. Pronotum punctured like the front. 

 Dorsulum, scutellum and mesopleurae not so strongly punctured as 

 the prothorax. Metanotum finely granular, bounded by a curved 

 furrow; metapleurae finely granular with a few transverse striae. 

 Femora robust, tibiae with stout spines. Abdomen microscopically 

 punctured, with a few larger punctures. Black; clypeus, except 

 anterior margin, mandibles except the apex, triangular spot on lower 

 inner orbits creamy-white; anterior femora beneath, all the tibia? and 

 tarsi rufous (the posterior tibiae and their tarsi are very dark, almost 

 piceous) . Wings dusky hyaline, costal apex of the posterior wings 

 with a large smoky spot; venation dark brown. 



Habitat. — Boulder, Colorado, June 1, 1908 (S. A. Rohwer), 

 caught flying over dry sand. 



Closely related to D. bidentatus , Ashm. and may be its male, 

 but the fore wings are without a cloud behind the radial cell, 

 the thorax is densely punctured, and there are perhaps other 

 characters, but the original description is very short. 



TRANS. AM. ENT. SOC, XXXV. (16) MARCH, 1909. 



