NEW AMERICAN BEES. 95 



appearance of 0. albolateralis, which is in other respects a very diffe- 

 rent species. Lower edge of clypeus black, slightly elevated, but not 

 peculiar in any way ; mandibles with two pointed teeth, and a trun- 

 cate subemarginate inner one ; hair of cheeks black, but a conspicuous 

 tuft of white hair on prothorax at sides of base of head ; tubercles 

 with white hair, pleura with black, sides of metathorax with white ; 

 dorsum of thorax with mixed black and white hair, the black pre- 

 ponderating, except posteriorly, along hind margin of scutellum ; 

 wings very smoky ; legs with short black hair, shining brownish on 

 anterior and middle tarsi ; abdomen with white hair on first segment 

 and extreme base of second ; the other segments with short black 

 hair, with a few light hairs intermixed on second and third, and much 

 glittering white hair on fifth ; scopa and hair at sides of abdomen 

 black. Superficially like 0. ivilmattce, Ckll., but distinguished by the 

 second s. m. more produced beyond the second r. n., the thorax above 

 with much more black hair, the larger ocelli and the tufts of white 

 hair on the face. From 0. giliarum, Ckll., it is known by the abun- 

 dant black hair on the thorax above, and the white hair on face. 

 From O.pikei, Ckll., it differs by the broader, deep blue face, &c. 



Hah. Northern Colorado, in the region near the foothills, 

 either in the vicinity of Boulder or Loveland (Clarence De Voss). 



Osmia (Acanthosmioides) nifoata, n. sp. 



(? . Length, 9 mm. ; dark greenish blue, the abdomen shining ; 

 hair of head and thorax entirely white ; flagellum black or almost 

 above, ferruginous beneath ; apical tooth of mandibles very long, the 

 other subobsolete, broadly obliquely truncate ; tegulaj blue in front ; 

 wings clear, a little stained along the veins ; legs black with strong 

 metallic tints, especially on the femora behind ; hair of legs partly 

 light and partly dark, the anterior and especially the middle tibige 

 conspicuously fringed with white hair behind ; hind femora strongly 

 swollen, their hair largely black ; hind tibiae conspicuously bent ; 

 inner side of hind basitarsus with dark fuscous hair ; first abdominal 

 segment with white hair, second with white and black, the others 

 with black, a little white near hind margin of third ; sixth segment 

 entire ; seventh bidentate ; second ventral longitudinally grooved, and 

 with a short compressed apical tooth, scarcely a third the length of 

 the segment. As in 0. odontog aster, the ventral tooth is sometimes 

 slightly bifid at the end. Distinguished from 0. odontogaster, Ckll., 

 by the entirely different colour, and broader abdomen. It is nearer 

 to Osmia asJmieadii (Acanthosmioides ashmeadii, Titus), but differs 

 from that by the much darker flagellum and the absence of a carina 

 on the first ventral segment. The eyes are sage-green. 



Hah. Troublesome, Colorado, 7345 ft., June 8th and 9th, 

 1908 ; three males (S. A. Rohwer). This is the first Acanthos- 

 mioides from the Eocky Mountains. 



