The specimens on which this paper is based are in the collection of the University of Nebraska, unless otherwide stated. Especial acknowledgments are due to Prof. Cockerell for specimens and suggestions, to Prof. Titus for specimens, and to Prof. Bruner for overseeing my work.

Halictus Montanus, n. sp. –Female: Black, head closely coarsely and deeply puncutred on the vertex, coarser along the inner orbits, less closely on the face below the antennæ clypesu sparsely and more coarsely punctured, fringed with golden hair at the apex; mandibles black, reddish at tips; antennæ black flagellum dark brownish beneath towards tip; pubescence of head and thorax griseous, slightly tinged with ochraceous on the thorax, thin on the disc of mesothorax, dense on pleura and cheeks; thorax closely and rather coarsely punctured; base of metathorax enclosed and finely rugose, truncation finely roughened and with large punctures; tegulæ large, testaceous, and with punctures anteriorly; wings slightly yellowish, clouded apically; nervures and stigma bright testaceous; legs black, tarsi and hind tibiæ behind ferruginous; pubescence of legs slightly ochraceous, on inner side of tarsi and hind tibiæ golden; inner hind tibial spur with many short blunt teeth; abdomen black, very finely punctured, apical margins of segments with yellowish-white hair bands, bases of segments 2–4 also showing slight hair bands; pubescence at base of first segment griseous, on discs of other segments black, not showing plainly except from the sides. Length, 12–14 mm.