,°), r ;0 Mr. T. D. A. Cockercll — Descriptions and 



The smallest American species of the genus ; nearest to 

 1). rnartii, Okll., from which it differs by the much smaller 

 size, very much finer punctures, more delicate thoracic spine, 

 and the much smaller (almost rudimentary) subapical lateral 

 spines of abdomen. The flagellum is only faintly reddish 

 beneath. 



Hob. Troublesome, Colorado, alt. 7345 ft., June 9, 1908 

 (S. A. Rohwer). 



Osmia bruneri, Ckll., $ . 



At Troublesome, Colorado, June 8 and 9, 1908, Mr. S. A. 

 Rohwer took both sexes of this species. 



The male is about 8 mm. long, short and compact like the 

 female, with the most brilliant colours. Clypeus a splendid 

 purple; sides of face largely green; vertex blue and purple ; 

 cheeks green ; thorax (including tegulaj) yellowish green, 

 bluer at sides ; abdomen brilliant green, bluer at sides and 

 apex ; legs blue-green, but tibice black or nearly on one side ; 

 hair of thorax above and occiput white without any admixture 

 of black; hair of vertex and clypeus black, but that of sides 

 of face white; apical segments of abdomen with black hair; 

 sixth segment with a distinct notch, seventh bidentate. 



In my table in Ann. & Mag. Nat. Hist., Aug. 1907, p. 123, 

 it runs to 0. bemiettce, Irum which it is easily distinguished 

 by the black hair of the clypeus, the shape of the abdomen, &c. 



Osmia yaudiosa, Ckll. 



c?. — Florissant, Colorado, at flowers of Mertensia lanceo- 

 lata, June 19, 1908 (S. A. Rohwer). 



The specimen has the abdomen more shiny than that of the 

 type, but I believe there is only one species. 



Diandrena nothocalaidis, Ckll. 



Troublesome, Colorado, at flowers of JSothocaluis euspidala, 

 June 9, many females (S. A. Rohwer). 

 Previously known only from Boulder. 



Andrena pyrrhactta, Ckll., var. mosina nov. 



$ . — Hair of face and front almost entirely black ; clypeus 

 finely punctured, with a very distinct smooth median line ; 

 much black hair at sides of metathorax ; hair of thorax above 



