merely, the sexes of a species; thence the numbers of the species in such genera are unduly augmented beyond their natural limits, from the fact of observation having neglected to associate the legitimate partners. In some of our native genera this same difficulty existed, which, however, is gradually diminishing as the authentic sexes are slowly discovered. Exotic bees exhibit also a peculiarity I had occasion to observe before, in reference to our own bees, amounting perhaps to a law, viz the more highly-coloured condition of the parasite, for we find all the parasitical bees of those latitudes, usually gorgeously arrayed in metallic splendour, as instanced in _Aglaë_, _Mesonychia_, _Mesocheira_, etc., and _Melissoda_ (my _Ischnocera_, in Lardner), is remarkably conspicuous for its long and delicately slender antennæ in the male, each joint of which is nodose at its extremity. The widely-distributed _Nomia_ seems to abound chiefly in India. It, although neither gay nor large, has, in its males, a distinguishing form of the posterior tibiæ, which is greatly incrassated or thickened; a peculiarity of structure found also in some other genera of _Hymenoptera_, and in several genera of the _Diptera_, giving the insects which have it a remarkable gait. The singularly anomalous distortion of these posterior legs is conspicuous also in the genus _Ancylosceles_, which is named in allusion to it. Another remarkable peculiarity is to be observed in the above genus, _Mesocheira_, as likewise in the superb _Acanthopus_, both of which genera have the spur of the intermediate leg palmated at the extremity, and the latter genus is further distinguished by its large size and splendid development, and by having the fifth joint of the tarsus of the posterior legs longer than the three preceding united, and covered with a pollinigerous brush as dense as that of the elongate first joint of the same limb. But the foreign genera which will be most interesting to the reader will, I expect, be those of _Trigona_ and _Mellipona_, which, in many peculiarities, seem abortive _Apes_. They seem nature’s first endeavour to construct _Apis_, for they have an apparently imperfect neuration of the wing, in which the external submarginal cell is unfinished. Their only separating distinction from each other is the difference in their mandibles, which in _Mellipona_ are broad and edentate, whereas in _Trigona_ they are also broad but denticulated. In _Apis_ these organs are merely irregularly enlarged at the extremity, and hollowed within, rather like a spoon, which structure would of course imply a difference of economy.