Subsection _a_. LINGUÆ EMARGINATÆ (with emarginate tongues). _Syn._ OBTUSILINGUES, _Westw._ _Three submarginal cells to the wings._ Genus 1. COLLETES, _Latreille_. (Plate I. fig. 1. ♂ ♀.) MELITTA * _a_, Kirby. _Gen. Char._: HEAD transverse, flattish; _ocelli_ in an open triangle on the vertex; _antennæ_ not geniculated, but slightly curved, filiform, short; joints, excepting the basal or scape, which is as long as five of the rest and slightly curved, nearly equal; _face_ beneath and within the insertion of the antennæ, slightly protuberant, laterally flat or concave; _clypeus_ convex, margined anteriorly, entire; _labrum_ transverse, slightly produced in the centre in front, and the process rounded; _mandibles_ obtuse, subbidentate; _cibarial apparatus_ short; _tongue_ deeply emarginate and bilobate, the lobes fringed with short setæ; _paraglossæ_ half the length of the tongue, abruptly terminating and lacerate, and setose at the apex; _labial palpi_ much shorter than the paraglossæ, four-jointed, the joints equal and each subclavate; _labium_ about the same length as the tongue, its inosculation acutely angulated; _maxillæ_ broad, lanceolate, the length of the tongue; _maxillary palpi_ six-jointed, not so long as the maxillæ, the two basal joints the longest, the rest equal, short, and subclavate, the apical one rounded. THORAX subquadrate, very pubescent, the prothorax inconspicuous; _scutellum_ transversely triangular or semilunate, _postscutellum_ lunulate; _metathorax_ abruptly truncated, and densely pubescent, especially laterally, for the conveyance of pollen; _wings_ with three submarginal cells and a fourth slightly commenced, the second and third each receiving about their centre a recurrent nervure; _legs_ all pubescent, the anterior and intermediate on their external surface chiefly, their _plantæ_ also setose; the posterior _coxæ_, _trochanters_, _femora_, and _tibiæ_ very hirsute, especially beneath, their _tarsi_ entirely setose; _claws_ bifid. ABDOMEN truncated at the base, subconical with a downward bias, the _segments_ with bands of closely decumbent nap, and the surface of all more or less deeply or delicately punctured; the basal segment in the centre, beneath, with a longitudinal tuft of long hair. The MALE differs in having the _mandibles_ more distinctly bidentate, and in being less densely pubescent, especially upon the legs. In general aspect it is very like its female. _Note._ The genus _Cilissa_ has, superficially observed, much of the habit of _Colletes_, particularly in the male of _Cilissa tricincta_. NATIVE SPECIES.