We have already noticed bees with metallic hues among the _Halicti_, and there are slight indications of it in some of the _Andrenæ_, for instance, in the _A. cinerea_ and the _A. nigro-ænea_, etc., but in none hitherto so absolutely is it exhibited as in this genus. The prevalent colour of the bees, that is to say, the ground colour of the integument, and not the fleeting one of the pubescence, is black or brown, but here we have a positive metallic tinge, which we shall again come across in many shades and hues in the genus _Osmia_. A second species of the genus was brought from Devonshire by Dr. Leach, and is in the collection of the British Museum, but no other specimens of the same species have since been found. The only flower which it has been noticed that they frequent is the Viper’s Bugloss (_Echium vulgare_). ------- Subsection 2. NUDIPEDES (naked-legged cuckoo-bees). a. _With three submarginal cells to the wings._ Genus 14. NOMADA, _Fabricius_. (Plates VIII., IX., X.) _Gen. Char._: HEAD transverse; _ocelli_ in a triangle on the vertex; _antennæ_ filiform, scarcely geniculated, the scape short, the basal joint of the flagellum subglobose, the second joint clavate, the remainder subequal; _face_ flat, or slightly concave, carinated longitudinally in the centre between the insertion of the antennæ; _clypeus_ subtriangular, convex, deflected at the lateral angles; _labrum_ subcircular, very gibbous and protuberant; _mandibles_ acute or subbidentate; _tongue_ long, acute; _paraglossæ_ about one-fourth its length, acute; _labial palpi_ two-thirds the length of the tongue, the two basal joints membranous, the basal one as long as the rest united, and tapering to its extremity, the second joint less than half the length of the first, and not wider at its base than the apex of the first joint, and tapering like that to its end, where it is acute, the third joint short, subclavate, and the terminal one-half the length of the preceding, very slender and linear; _labium_ about one-half the length of the tongue, and at its inosculation produced obtusely in the centre; _maxillæ_ subhastate, about the length of the tongue; _maxillary palpi_ six-jointed, the basal joint short, robust, subclavate, the second the longest, and with the rest tapering in substance and diminishing in length to the extremity, the terminal joint being very little shorter than the preceding. THORAX ovate; _prothorax_ inconspicuous, or distinct and angulated laterally; _mesothorax_ glabrous, deeply punctulated; its _bosses_ conspicuous and prominent; _scutellum_ divided into two very prominent tubercles; _post-scutellum_ linear, convex; _metathorax_ with a triangular space at its base, and declining to the insertion of the abdomen; _wings_ with three submarginal cells, and a fourth very slightly commenced, the first as