The male _Apathi_ can only be distinguished from the male _Bombi_ by familiarity with specific characteristics, or by the examination of the trophi. But the former is the more certain mode of separation, as the trophi in _Bombus_ vary in some species, but not sufficiently to authorize generic subdivison. General appearance will mark where they approximately belong. The length of their antennæ sufficiently distinguishes them as males, and they may be taken with impunity in the fingers from flowers for examination, being, like all the male aculeate _Hymenoptera_, unarmed with stings. The female _Apathi_ may be superficially distinguished from the female _Bombi_, which they most resemble, exclusively of the generic characters of the convex and subpubescent external surface of the posterior tibiæ and the trophi, also by their abdomen being considerably less hirsute than that of the genuine _Bombi_, in which it is entirely covered with dense shaggy hair, whereas in _Apathus_ there is a broad disk upon its surface nearly glabrous. If I remember rightly, it is the male _Apathi_ only, and not the male _Bombi_, which emit on capture a pleasantly fragrant odour of attar of roses. The table will suffice for distinguishing the male _Apis_ from all other male _Apidæ_, and which has a further peculiarity exhibited by no other of our native bees, in the conjunction upon the vertex of the compound eyes, in front of which, upon the frons, the simple eyes or ocelli are placed in a very slightly-curved line. These indications are enough to enable the beginner to work his way smoothly, and a little practice will soon render these observations superfluous. The economy of nature is so perfect that wherever we can trace a difference, we may assume that a reason and a purpose exist for the variation. Thus we do not know why some bees have three submarginal cells to their wings, and others only two. Nor do we know what governs their variety of shape. The deficiency we might think implied inferiority; but this cannot be, for those with most frequently the smaller number, viz. the artisan bees, are, in the majority of cases, the most highly endowed, and have the most special habits. In the relative numbers of the maxillary and labial palpi, there are remarkable differences, the reason for which we cannot trace, for, as before observed, we do not know even their function, which would perhaps guide us to other views. Their normal numbers are six maxillary, and four labial palpi. The latter take remarkable relative development and peculiarity of insertion and form, especially in the _Apidæ_; but throughout the whole series of our bees, they are never reduced to fewer than their normal number, whereas the maxillary palpi never have similarly large development of structure, and are variously modified in number and consistency from the typical or normal condition.