As Mr. Kirby’s work is in few hands, or perhaps not readily accessible, I will give here a summary outline of it, with the names of the genera with which his families coincide.
In this work he established only two named genera—_Melitta_ and _Apis_.
His genus _Melitta_, which is equivalent to the subsequent subfamily _Andrenidæ_, he divides into two sections, * and * *, the first containing two families, _a_ and _b_, (these we call genera, and they are now named _Colletes_ and _Prosopis_); the second section * * contains three families, _a_, _b_, _c_, (_a_, is _Sphecodes_, _b_, _Halictus_, and _c_ comprises our three genera, _Andrena_, _Cilissa_, and _Dasypoda_.)
His genus _Apis_ he also divides into two sections, * and * *; the first is subdivided into two families, _a_ and _b_ (our genera _Panurgus_ and _Nomada_); and the second is divided into five subsections, _a_, _b_, _c_, _d_, _e_; _a_ and _b_ constitute families (our genera _Melecta_ and _Epeolus_). The subsection _c_ is divided into two parts, 1 and 2, the first containing the two divisions _α_ and _β_, each comprising a family (our genera _Cœlioxys_ and _Stelis_); and the second is divided into the four families, _α_, _β_, _γ_, _δ_, (_α_ being the modern _Megachile_; _β_, _Anthidium_; _γ_, _Chelostoma_ and _Heriades_ conjunctively, and _δ_ is our _Osmia_). The subsection _d_ has two subdivisions, 1 and 2, the first being a family (our _Eucera_); and the second is divided into the two families _α_ and _β_ (_α_ comprising our _Saropoda_, _Anthophora_, and _Ceratina_), and the family _β_, consisting of the genus _Xylocopa_, then supposed to be indigenous, but whose native occurrence has not been substantiated.
The fifth subsection, _e_, is split into two divisions, 1 and 2, each containing a family (1 is our _Apis_, and 2, our _Bombus_).
In this last of his families Mr. Kirby had already noticed, with the same sagacity with which he had previously conjectured the cuckoo-like habits of some of the solitary bees, the distinctive structure of some of the species, which incapacitated them from providing the sustenance of their own young, and which thus reduced them to the same category; but he left the idea in its supposititious condition, being too modest to use it as a mark of separation, but which Newman, on our side of the Channel, and St. Fargeau on the other side, subsequently, and both nearly about the same time, but with the advantage in favour of Newman, distinguished, and separated generically, respectively by the names of _Apathus_ and _Psithyrus_; the former, having the priority, is adopted, according to the rights of precedence in nomenclature.
