The exotic genera of bees which are peculiarly noticeable, either from splendour, size, or remarkable eccentricities of structure, are numerous. Tropical and sub-tropical regions of course abound with them, in individuals, in species, and in genera; and when we reflect upon the riches of the flora of those countries, which is perpetuated mainly by the agency of insects, amongst which, in fulfilling this indispensable demand, bees, as I have reiterated, are pre-eminently conspicuous, we shall not even wonder that their number, although excessive in the extreme, is considerably aided, in many cases, in the performance of this task, by peculiarities of structure. Thus, the splendid Brazilian genus _Euglossa_, although not conspicuous for size, is remarkably so for the enormous development of its posterior tibiæ, which form very large triangles, compared with the size of the insect, deeply hollowed for the conveyance of pollen. Its tongue also, from the length of which the genus derives its name, is, when extended, more than twice the length of the body, and with which it is enabled to reach the nectarium, seated within the depths of the longest tubes of flowers. Other exotic bees, further to aid them in collecting pollen, in addition to the dense brushes with which their posterior legs are variously covered, have each individual hair of these thick brushes considerably thickened by hairs given off laterally, and in some cases these again ramify. Sometimes, in variation, the simple, single hairs have a spiral curve, which almost equally enlarges the activity of their operation. This is also the case with two very hairy-legged genera of our native bees, proximately allied to each other in the methodical arrangement, _Dasypoda_ and _Panurgus_, the hair of whose posterior legs have this spiral twist. The most hairy-legged exotic bees are essentially the genera _Centris_ and _Xylocopa_. Of the habits of the former we know nothing, but those of the latter we are intimately acquainted with, through the elaborate descriptions given by Réaumur and the Rev. L. Guilding, the latter of whom made his observations upon a species found in the island of St. Vincent’s, in the West Indies. This last genus exhibits in some of its species the giants among the bees, and one is especially so, a native of India, the _Xylocopa latipes_, which is an inch and a quarter long, and more than three inches in the expansion of its black, acute wings; and it is also noticeable from the anterior tarsus in the male being greatly dilated and white, the bee itself being intensely black, and which in this same sex has enormous eyes united at the vertex, as in the male _Apis_, or drone. In this genus, as in many other genera of bees, there is often a great discrepancy in the appearance of the sexes, they being so totally dissimilar that no scientific skill has hitherto been able to discover a clue for uniting together correctly, by scientific process