AMERICAN HYMENOPTERA. 107 



Osniia4-dentata.— '^.— Small, bluish-green, opaque; head and thorax 



densely punctured, clothed with a long whitish pubescence, very dense on 



clypeus, the anterior margin of which is subsinuate; antenna reaching to 



the seutellum, black; tegulse piceous ; wings faintly tinged with dusky; legs 



slender, simple, clothed with pale pubescence, tips of tarsi dull 



W testaceous; abdomen narrow, convex, shining, finely punctured, 

 clothed with a short pale glittering pubescence, more conspicuous 

 on the sides and on lateral apical margin of the segments; apex 

 with four prominent teeth (as in figure), sixth segment being broadly sinuate 

 on each side, with the lateral angles prominent and acute, seventh segment 

 bidentate; venter steel-blue, second segment very large, broad, transversely 

 impressed near base, apical margin subsinuate. Length .35 inch. 



Hah. — New York, (Comstock). Easily recognized by the shape of 

 the two apical segments of the abdomen. 



Osmia inurbaiia.— '^.— Small, brassy-green; head and thorax sub- 

 opaque, closely and finely punctured, thickly clothed with a long pale pubes- 

 cence, tinged with dull ochraceous above, that on clypeus very dense and 

 white; antennae nearly as long as head and thorax, black; tegulse piceous; 

 wings faintly dusky on apical margin; legs black, clothed with pale pubes- 

 cence, that on femora behind long; abdomen shining, rather thickly clothed 

 with a short pale ochraceous sericeous pubescence, which is long on basal 

 segment; apical margin of sixth segment subsinuate on the sides and deeply 

 notched in the middle, seventh segment acutely bidentate. Length .35 inch. 



Hah. — Colorado, (Ridings, Morrison). Four specimens. This is 

 allied to ruatica. Cress., which is clothed with a bright fulvous pubes- 

 cence and has the apical margin of sixth abdominal segment strongly 

 sinuate laterally and only slightly notched medially. 



Osniia bella. — %. — Small, blue, green, sometimes golden-green; head 

 and thorax densely and strongly punctured, clothed with long whitish pubes- 

 cence, which is slightly mixed with black on head and thorax above, on 

 clypeus it is dense and white; mandibles and antennae black, the latter reach- 

 ing to seutellum; wings faintly dusky on apical margin; legs bluish-green, 

 clothed with pale pubescence, which on basal joint of tarsi beneath is black; 

 abdomen short, convex, shining, feebly j^unctured, thinly clothed with a short 

 pale pubescence, long on basal segment, and black on apical segments; sixth 

 segment slightly produced at apex and obtusely emarginate on apical middle, 

 seventh segment acutely bidentate; venter steel-blue or purple, second seg- 

 ment very large and fringed at apex with blackish pubescence. Length 

 .35 inch. 



Hah. — Colorado, (Morrison). Five specimens. A handsome little 

 species, remarkably brilliant in color, which varies through all the 

 shades of blue and green. 



Osmia exigutia. — %. — Very small, green, tinged with blue; head and 

 thorax densely and finely punctured, clothed with a long ochraceous pubes- 

 cence, which is dense and pale on clypeus, and whitish on thorax beneath; 

 head larger than usual ; antennae black, reaching to seutellum; tegulse golden- 

 green; wings faintly dusky at apex; legs green, clothed with pale pubescence, 



