28 [Aprii: 



finely punctured; face thickly clothed with loBg yellowish-white pu- 

 bescence, that on the vertex and cheeks long and sparse ; antennre 

 about twice as long as the head, black, the flagcUum beneath rufo-tes- 

 taceous. Thorax black with a blue-green reflection, densely and finely 

 punctured, clothed, especially on the sides and beneath, with rather 

 long yellowish-white pubescence ; tegulae black, shining. Wings hya- 

 line, apical margins faintly clouded, nervures black. Legs black with 

 a slight greenish tinge, shining, clothed with short pale glittering pu- 

 bescence; the tarsi beneath with yellow pubescence, the apical joints 

 rufo-piceous. Abdomen rather short, subglobose, black faintly tinged 

 with blue and purple, very closely, finely and uniformly punctured, 

 densely clothed above with very short pale fuscous pubescence which 

 has a pale sericeous appearance in certain lights; sides of the basal 

 segment and also of the apical segments have the pubescence rather 

 long and whitish ; apical margin of the sixth segment sinuate on each 

 side and rather deeply and obtusely notched in the middle; apical seg- 

 ment bidentate ; beneath, the ventral segments are flat and fringed 

 posteriorly with yellowish-white pubescence. Length 3f lines. 



Hah. — Rocky Mountains, Colorado Territory. Coll. Ent. Soc. Phil. 



Somewhat resembles 0. j^urpurea, but the punctation of the abdo- 

 men is finer and the segments have no appearance of an apical whitish 

 fringe which is more or less conspicuous in that species. 



17. 0. simillima, Smith. 



<)s)nia simillima. Smith, Brit. Mus. Cat. i, p. 112, % 9 (1854.) 



Femab'. — Head rather large, as wide as the thorax, bluish-green, 

 densely and rather finely punctured, thinly clothed with whitish pu- 

 bescence ; clypeus more strongly punctured, apical margin truncate ; 

 antennas short, black. Thorax bluish-green, densely and finely punc- 

 tured, clothed with rather long whitish pubescence. Wings sub hya- 

 line, their apical margins faintly clouded. Legs black, with a short 

 pale pubescence ; the tarsi beneath with blackish pubescence. Abdo- 

 men subglobose, blue, tinged with green, polished, rather finely punc- 

 tured ; apical margin of the segments smooth ; the segments above 

 clothed with short whitish pubescence, that on the basal segment long- 

 est and that on the sides and on the apical segment more dense ; be- 

 neath, the ventral scopa is dense and black. Length 4f lines. 



" Male.. Length 4 lines. — Head and thorax of a bronzed green, 



