of observations, and not confined to one locality, they would form strong and remarkable instances of a defective analogy in nature’s workmanship, and suggest looking further for the causes of so extraordinary an anomaly, and urge us to endeavour to trace the equivalent which supersedes it. The main subdivision of the _Apidæ_ results from the habits of the insects, which divides them into SOCIAL and SOLITARY. The only tangible characters the social tribes present to distinguish them from the solitary is the glabrous surface of the posterior tibiæ, with their lateral edges fringed with bristles slightly curved inwards, and which form, with the slightly indented surface of the limb, a sort of natural basket for the conveyance of pollen or other stores to the nest. This, however, has not been made use of as a main feature for scientific distribution, although they might follow the _Dasygasters_, as _corbiculated bees_, or little basket bearers, in which case they would form as pertinent a group as any of the rest, and the whole distribution of the bees, _Apidæ_, would then rest upon the absence of, or the mode in which the polliniferous organs were present. But the wonderful attribute of their extraordinary instinct prohibits their being treated with the rest in a consecutive line, and renders it rationally imperative that all the _Cenobites_ should group together in a section by themselves, and separate from the rest. Therefore in my arrangement I have not availed myself of this very natural character, and here indicate it, to show that I have not passed it from not noticing it. Although the division into social and solitary yields in itself no tangible character whereby the insects may be separated, it being wholly empirical, yet is it so natural and necessary that it is impossible to gainsay it. We find the solitary section readily resolve itself into groups or subsections, determined by positive structural characters, indicative of certain habits, and having a conforming economy, besides which they are equivalents.