These, perhaps the most conspicuous of our native bees, certainly the largest, and probably the most generally known after the domestic bee, have their scientific generic name from _βόμβος_, an imitative word, made to indicate the sound of the hum of the insects themselves. They have many popular names such as bumble bees, dumbledors, humble-bees, and in Scotland they are called foggie bees. They consist of three sexes, males, females, and neuters, which differ considerably in size, the females being very much the largest, and the neuters the smallest. Of course, individually, like all other insects, there is much variation among them in the intensity or diversity of the colouring of their pubescence, from which it is chiefly that they derive their specific distinctions; in the relative sizes of individuals also there are great differences. It is the males, as is usual among the bees, which are the gayest in their attire, and take the widest range of variation, and sometimes so much exceed the typical specific character in their markings as to require experience to identify them, and to place them correctly with their true species, which can only be ascertained with certainty by the examination of the male organs of generation, which differ in the various species, but are undeviating in their specific uniformity. Of this character, which I was the first to discover as being of specific value for critical determination in the separation of the species of very difficult insects, I was enabled to make important use in the genus _Dorylus_, in a monograph on the _Dorylidæ_, an exotic family proximate to the ants, and which was published in Taylor’s ‘Annals of Natural History’ for May, June, and July, 1840. The females and neuters of _Bombus_ are less subject to such extensive dissimilarity, and may be usually associated, by their pubescence, in their legitimate groups. Form also frequently lends its aid as subsidiary to their specific identification.