36-4 Mr. T. D. A. Oockerell — Descriptions and 



Osmia ajyrilinay sp. n. 



^. — Lenatli about 7 mm.; anterior wing about 5; width 

 of abdomen 2^. 



Similar to 0. imhatiUce, but liair of tliorax above pale 

 reddish, without black hairs interspersed. Head larger, much 

 wider above. Abdomen broader, more globose, and yellowish 

 green ; sixth segment with a conspicuous rounded notch. 

 Tiie antennae are entirely dark ; hair of face pale, white 

 below, yellowish above, without any black ; vertex with an 

 admixture of black hairs ; cheeks with long black hairs in 

 front, but the hair otherwise white. Wings dusky. Legs 

 with green tints. Abdomen with pale hair, but a good deal 

 of black from middle of third segment on ; seventh segment 

 bi dentate. 



Known from 0. proxima by the dark flagellum and dark 

 hairs on cheeks and vertex. Similar characters and the 

 structure of the sixth abdominal segment separate it from 

 0. pumila. It is an Osmia s. str. in the sense of Robertson. 



Hub. Boulder, Colorado, at flowers of Pulsatilla hirsutis- 

 sima, April 20, 1906 (TF. P. d) T.D.A. Cocherell) ; Boulder, 

 May 1906 {S. A. Rohwer). Four specimens. 



Osmia pJiacelice, sp. n. 



2 . — Length 8 mm.; width of abdomen 3. 

 Blue-green, with yellowish-green tints about the head and 

 thorax. Legs black, the hind femora faintly greenish ; scopa 

 black, some white hairs at extreme sides. Hair of head and 

 thorax mainly white, but many coarse black hairs on face and 

 vertex and fewer on scutellum and mesothorax ; seen from 

 above, the hair of the clypeus appears short and black and 

 that on each side of face longer and nearly all silvery white ; 

 head and thorax very densely punctured ; head ordinary, 

 clypeus normal, mandibles 3-dentate, antenna? short and 

 black ; hair of legs largely black, that on inner side of middle 

 and hind tarsi nigro-fuscous ; tegulge largely green. Wings 

 dusky, first r. n. joining second s.m. at least three times as 

 far from base as second from apex. Abdomen shining blue- 

 green, hind margins of segments concolorous ; hair of second 

 segment white but very short and scanty, with longer dark 

 hairs toward sides ; following segments with tiie usual dark 

 hairs, but the apical one, except at apex, with fine silvery 

 tomentum. 



Distinguished from 0. faceta, Cress., by the smaller size, 

 greener abdomen, and colour of huir on clypeus. It looks 



