NEW AMERICAN BEES. 95 
appearance of O. 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 O. wilmatte, 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 O. giliarwm, Ckll., it is known by the abun- 
dant black hair on the thorax above, and the white hair on face. 
From O. pikei, Ckil., it differs by the broader, deep blue face, &c. 
Hab. Northern Colorado, in the region near the foothills, 
either in the vicinity of Boulder or Loveland (Clarence De Voss). 
Osmia (Acanthosmioides) nifoata, n. sp. 
3. 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 ; tegule 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 tibiz 
conspicuously fringed with white hair behind ; hind femora strongly 
swollen, their hair largely black; hind tibiz 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 O. odontogaster, the ventral tooth is sometimes 
slightly bifid at the end. Distinguished from O. odontogaster, CkIL., 
by the entirely different colour, and broader abdomen. It is nearer 
to Osmia ashmeadiz (Acanthosmioides ashmeadir, 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. 
Hab. Troublesome, Colorado, 7345 ft., June 8th and 9th, 
1908 ; three males (S. A. Rohwer). This is the first Acanthos- 
mioides from the Rocky Mountains. 
