The types of the spcies described below are in the author's collection except for the Acanthosmioides, which are in Prof. T. D. A. Cockerell's collection.

Osmia (Acanthosmioides) uncinata n. sp.

Male: Length 10 mm.; head and thorax green, the cheeks and pleura bluer, the abdomen blue, slightly greener posteriorly, the posterior margins of the tergites concolorous; flagellum crenulate, the under side brownish red; mandibles black, their bases greenish; legs black except for the green femora and rufescent claw joints of tarsi; hind tibiae perhaps faintly greenish basally; tegulae black, green anteriorly; hind basitarsus widest apically, tapering basally; head and thorax closely punctate, but the vertex and scutum not blackish; wings hardly dusky, the basal vein meeting transverse median, the second abscissa of cubital vein nearly twice as long as fourth; scutellum with a longitudinal median line, which is not distinctly polished; pubescence of head and thorax white, that of clypeus dense and erect as in other species of this subgenus; pubescence of abdomen white, the third tergite with a few black hairs posteriorly on dorsum, tergites four to six with more abundant black hairs intermixed among the pale; venter of abdoinen with some dark hairs among the pale; apex of abdomen normal for the subgenus, the teeth of seventh tergite rounded; process of second sternite not compressed apically, but rather narrowly rounded when seen from below, the base (in same view) widened; seen from the side, the apex of the process is minutely hooked on ventral side; ventral side of process, especially basally, somewhat excavated, but not grooved.