This genus has been named without any reference to any peculiarity, Dr. Leach having applied a Proper name to it to designate it.
The Cilissa tricincta is perhaps most like the larger species of the genus Colletes, both in markings and in the form of the body, but in resemblance of form the second species participates. Although robust insects, and as large as the larger Andrenæ, they are yet unprovided with the same ample means for conveying pollen, being destitute of the lock of hair upon the posterior trochanters and the sides of the metathorax are less densely pubescent. The ground colour is brown. Their economy is assumed to resemble that of Andrena, although it has not been so closely investigated; for my own part I have never had the opportunity of tracing it to its nidus, having always captured the species upon flowers. They are fond of the trefoil (Trifolium repens), and the C. chrysura frequents the Campanula rotundifolia, as well as the flowers of the throatwort (Trachelium). In their excursions they are usually accompanied by their males. Both species are found in the south and west of England.
Section 2. With entire paraglossæ.
Subsection c. Linguæ Acutæ (acute tongues).
a. With three submarginal cells to the wings.
Genus 6. Halictus, Latreille.
Melitta ** b, Kirby.
Gen. Char.: Head transverse, flattish, scarcely so wide as the thorax; ocelli in an open triangle on the vertex, which is flat; antennæ short, filiform, geniculated, scape quite or more than half as long as the flagellum; face flat, excepting in the centre just below the insertion of the antennæ, where it is protuberant; clypeus transversely lunulate, very convex; labrum subquadrate, very convex, with a central, linear, carinated appendage in front, nearly as long as the basal portion; cibarial apparatus moderate; tongue very acute and delicately fringed with short hair; paraglossæ acute, about half the length of the tongue; labial palpi not quite so long as the paraglossæ, the basal joint very long, the rest decreasing gradually in length; labium about as long as the tongue, its inosculation emarginate; maxillæ subhastate, rather longer than the tongue; maxillary palpi filiform, the basal joint the shortest, second the longest, the rest decreasing in length. Thorax oval, usually pubescent, sometimes glabrous; prothorax inconspicuous, as are the bosses of the mesothorax; scutellum and post-scutellum lunulate, the former convex; metathorax gibbous or truncated, but laterally pubescent even in the glabrous species; wings with three submarginal cells, and a fourth sometimes commenced, the second subquadrate and receiving the first recurrent nervure close to its extremity, the second being received beyond the centre of the third submarginal cell legs all setose, but the setæ not very long, and the posterior coxæ and trochanters have long hair beneath; the claws bifid. Abdomen ovate, the terminal segment with a longitudinal linear incision in its centre.
The MALES differ in having the antennæ as long or longer than the thorax; the labrum transverse, linear, and the abdomen usually elongate and cylindrical, and much longer than the head and thorax.