% 



REVISION OF THE GENUS EXETASTES CUSHMAN 281 



22. EXETASTES CONCAVUS. new species 



Very similar structurally to the two foregoing species, but at once 

 distinguishable from both by the entirely black mesoscutum. From 

 the above description of crassiscul2)tus it differs as follows: 



Female. — Malar space slightly shorter; eye as long as width of face; 

 scutellum less strongly elevated, less precipitous behind; nervulus 

 interstitial or nearly so. 



Clypeus and mandibles black; scape at most faintly reddish; 

 flagellum without trace of annulus; thorax black with only small 

 humeral angles of pronotum and an indefinite spot on scutellum ferru- 

 ginous ; coxae entirely and hind femur below more or less black ; hind 

 tibia somewhat infuscate, basitarsus black; first tergite black at base. 



Male. — Essentially like female, but scape paler, scutellum entirely 

 olack, petiole more extensively black. 



Type locality. — Grant, Park County, Colo. 



r?/pe.— U.S.N.M. no. 51809. 



Remarks.— One of each sex, the holotype female taken at 9,000 feet, 

 July 24-29, 1922; the allotype, labeled simply "Colo., C. F. Baker." 



23. EXETASTES MATRICUS Provancher 



Plate 16, Figure 9; Plate 17, Figures 22, 42; Plate 18, Figure 6.3 



Exetasies matricus Provancher, Nat. Can., vol. 11, p. 213, 1879, female; Petite 

 faune entomologique du Canada . . ., vol. 2, Hymen., p. 385, 1883, female. 



This and the seven following species form a group differing from 

 all the other groups by the form of the scutellum, which is more or 

 less distinctly flattened above, steeply pjecipitous behind, and more 

 or less distinctly carinately margined laterally at least toward base. 

 In addition the eyes are large, strongly convex and convergent below; 

 the clypeus long, weakly divided into basal and apical portions and 

 apically emarginate; the malar space long; the antennae long and 

 slender and more or less attenuate apically; the legs slender with 

 very long calcaria; the abdomen slender; and the ovipositor straight, 

 the sheath from three-fom-ths as long to fully as long as first tergite. 



Female. — Length 12 mm, antennae 10 mm. 



Head hardly half as thick medially as broad, occiput moderately 

 concave, temples nearly flat, strongly receding, about two-thirds as 

 long as short diameter of eye, polished, virtually impunctate; frons 

 concave, mat, sparsely punctate; face more than half as long as broad, 

 medially elevated, concave laterally above, mat, densely punctate; 

 clypeus three-fourths as long as broad, distinctly divided by sculpture 

 but rather weakly so by elevation, emarginate and with a more or less 

 distinct median groove apically; head below eyes very narrow, the 

 cheeks straight, their extended angle very sharply acute; malar space 

 three-fourths as long as basal width of mandible; mouth barely broader 



