This is a rather smnall, robust, not densely pubescent species. It is black, except for the hind femora and inner sides of the hind tibiae, which are red. The posterior legs are unusually robust in both sexes. This species is super- ficially similar to the group of bigeloviae, but differs from these as well as from all other known species except titusi by the large teeth of the outer margin of the inner hind tibial spurs.
Female: Inner margins of eyes convetging below; transfacial line consider- ably longer than facial line; under side of flagellum brown; head closely and rather finely punctured except for the smooth apical margin of clypeus; clypeus with distinctly concave apical truncation (similar to but slightly shallower than that of dimalla) nearly as long as distance from end of truncation to lateral angle of clypeus, often reddish, margin of clypeus between these two points convex; distance from first to. third mandibular tooth less than width of eye or length of last three antennal segments; mandibles reddish subapically; punctures of clypeus a little larger and perhaps closer than those of vertex, those of cheeks finer than those of vertex; cheeks narrower than eyes seen from side; anterior ocellus posterior to midpoint between bases of antennae and posterior edge of vertex; distance between posterior ocelli slightly greater than or equal to distance to nearest eye margin or to posterior edge of vertex. Scutum without pair of pubescent spots anteriorly; punctures of scutum and scutellum larger than or as large as, those of vertex, and separated by a little shiny surface; mesepisterna similarly or a little more finely punctured; wings slightly dusky; tegulae dark testaceous; posterior tibiae except outer sides and posterior femora red; hlind tibial spurs robust, black, strongly curved apically, inner margin of inner spurs with about seven rather large teeth, outer margin with about seven very large teeth; inner margin of outer spurs with about two rather large teeth, outer margin with about three rather large teeth. Abdomen with strong punctures, those of dorsum of second tergite separated by about their diameters; punctures of fourth to sixth tergites, and of sides of all tergites, close; tergites one to five with apical bands of white pubescence, and with apical margins testaceous; scopa white. Length 5'/2 to 7 mm.
Male: Similar to female. Face, especially clypeus, densely covered with pubescence; clypeus with distinct apical concavity less than half as broad as basal width of clypeus and demarked by evident angles; punctures of upper parts of mesepisterna widely sparated; small segments of tarsi rufescent; inner margin of inner hind tibial spurs with about eight small teeth, all on basal half of spurs, outer margin with two large teeth medially, a small one distad to them and about two small ones basad to them; outer spur with about four oblique teeth on each margin. Abdomen with punctures coarser than in female, though not as coarse as those of scutum; outer teeth of sixth tergite acutely pointed, longer than wide; median teeth nearly parallel sided apically, nearly twice as long as broad, broadened basally, concavity between them longer than a semicircle. Length 5 to 5,/2mm.
In many females the punctures of the abdomen are coarser than described, more as in the male. The male of this species is here described for the first time.
This species occurs in the deserts of southern California, north as far as Inyo County.
CALIFORNIA: Mazourka Canyon, Inyo Mountains, Inyo County, May 25, 1937, on Parosela fremoniii (C. D. Michener); six miles south of Olancha, Inyo County, June 20, 1937 (E. Gehrhardt); Andrade, Imperial County, March 6, on Larrea (T. D. A. Cockerell) Dos Palmos, Riverside County, March 19, 1934 and March 28, 1934 (from Cazier and Bohart); Cathedral City, Riverside County, April 10, 1936, on Larrea gluiinosa (C. D. Michener); Taquitz Canyon, Riverside County, April 16, 1938, on Larrea glutinosa (G. E. and R. M. Bohart); Palm Canyon, April 5, 1925, on same flower; two mile south of Oasis, March 8, 1936, on same flower, and April 19, 1925, on Cercidium torreyanum; La Quinta, March 2 and 17, 1934, on Larrea glutinosa& and March 4, 1936, on Hypiis emorvi; Box Canyon, April 13, 1934, on Cercidium forreyanum; Painted Canyon, April 18, 1925, on same flower (All P. H. Timberlake). Type: female; from ten miles east of Borego Valley, California, on loan deposit at the California Academy of Sciences.
The discovery of the male and of reliable generic characters in the females shows clearly that femorata is an Ashmeadiella, not an Osmia as originally describ