104 E. T. CRESSON. 



Osuiia arniaticeps. — 9 -—Black; head and thorax closely and strongly 

 punctured ; head quadrate, clothed above with black pubescence slightly mixed 

 with pale on each side of vertex and on occiput; cheeks broad, sparsely and 

 finely punctured and shining, on each side beneath near base of mandibles 

 a long subacute tooth; face nude; clypeus flat, smooth and polished, a deep 

 fovea on each side near base and the apical middle with two short obtuse 

 teeth; mandibles very long, acute, rugose, having on the outer margin a 

 narrow groove; thorax above clothed with long pale pubescence, slightly 

 mixed with black, on the sides and beneath the pubescence is black; disk of 

 mesothorax sparsely punctured and polished; wings dusky, darker on apical 

 margin; legs clothed with black pubescence; abdomen slightly tinged with 

 blue, shining, delicately punctured except at tip where the punctures are close 

 and rather deep, clothed with short black pubescence, except on first segment 

 where it is long and whitish, slightly mixed with black; ventral scopa black. 

 Length .45 inch. 



Hab. — Colorado, (Ridings, Morrison). Three specimens. Easily 

 recognized by the elongate-quadrate head, which is armed on each 

 side beneath with a rather long conspicuous tooth. 



Os^mia qiistdi'iceps. — 9- — Black; head and thorax densely punctured; 

 head quadrate, thinly clothed above with long black pubescence, cheeks broad, 

 flattened, polished and sparsely punctured; face nude: clypeus smooth, pol- 

 ished, concave, deeply impressed on each side, the apex produced, and emar- 

 ginate or notched in middle; mandibles large, rugose, acute at tip, with a deep 

 groove on outer margin; thorax thickly clothed with long black pubescence, 

 which is sparse on disk above; mesothorax sparsely punctured and polished 

 on posterior middle; wings fuscous, with a subhyaline mark before apex; legs 

 with black pubescence; abdomen rather strongly tinged with blue, finely punc- 

 tured, shining, the pubescence short and black, except on first segment where 

 it is long; ventral scopa blacjj. Length .50 — .60 inch. 



Hah. — California, (H. Edwards). Eight specimens. In shape this 

 resembles armatireps, but the head is not armed beneath, and the 

 pubescence is entirely black. 



Oisniia niaura. — 9- — ^Entirely deep black; head and thorax densely 

 punctured, clothed with black pubescence, which is dense on the face, thorax 

 and sides of abdomen; head subquadrate; apical margin of clypeus broadly 

 emarginate, the lateral angles prominent; disk of thorax almost nude; wings 

 dusky on apical margin; legs with black pubescence; abdomen shining black, 

 delicately punctured; ventral scopa black. Length .46 inch. 



Hah. — California, (H. Edwards). One specimen. This is easily 

 distinguished by the body being entirely deep black. 



Osniia cobaltina. — 9- — Brilliant deep blue or purple; the head and 

 thorax changing to green, densely punctured, thinly clothed with pubes- 

 cence, black on head, and pale mixed with black on thorax; clypeus always 

 dark blue, with fuscous pubescence at apex which is truncate; wings dusky; 

 legs green or blue, with short black pubescence; abdomen shining, finely 

 punctured, deep blue, purple or green; ventral scopa black. Length .35 — 

 .40 inch. 



