As this work will impinge but very incidentally upon the internal organization of the bee, it is unnecessary to be more explanatory. All that I shall have to notice here are those portions of the external structure which have any special bearing upon the economy and habits, or upon the generic and specific determination of the insects, and to which therefore I shall specially limit myself. [Illustration: Fig. 5.—Front of the head of the bee. _a_, vertex; _b_, face; _c_, ocelli or stemmata; _d_, compound eyes; _e_, clypeus; _f_, mandibles; _g_, labrum; _h_, lingual apparatus folding for repose.] The _head_ is the most important segment of the insect’s body, if we may elevate to such distinction any portion, when all conduce to the same end, and either would be imperfect without the other, yet we may perhaps thus distinguish it from the rest as it exclusively contains that higher class of organs, those of sense, which are most essential to the functions of the creature. The head consists of the _vertex_, or crown; the _genæ_, or cheeks; the face; the _clypeus_, or nose; the compound eyes; the _stemmata_, or simple eyes; the _antennæ_, or feelers, and the _trophi_, or organs of the mouth collectively. The _thorax_, the second segment, carries all the organs of locomotion. It consists of the _prothorax_ or collar, which carries beneath the anterior pair of legs; the _mesothorax_, or central division, with which articulate laterally above the four wings, the anterior of which have their base protected by the _squamulæ_, or epaulettes, or wing-scales, and beneath it carries the intermediate pair of legs; the _metathorax_, or hinder portion, which has in the centre above, behind the _scutellum_, the _post-scutellum_, and at the extremity of this division just above the articulation of the posterior legs is attached the last segment of the insect,—the _Abdomen_. The _vertex_, or crown of the head, is that portion which lies between the upper extremities of the compound eyes. Upon the vertex are placed the _stemmata_, or _ocelli_ (the simple eyes), in a curve or triangle; they are three in number, and are small, hyaline, circular protuberances, each containing within it a lens; sometimes they occur very far forward upon the face, especially when the compound lateral eyes meet above, as in the male domestic bee or drone. The uses of these simple eyes, from the experiments which have been made, seem to be for long and distant vision. To test their function, Réaumur covered them with a very adhesive varnish, which the bee could not remove, and he then let it escape. He found upon several repeated trials, that the insect always flew perpendicularly upwards, and was lost. Although this was anything but conclusive as to the uses of these eyes, it would seem that by losing the vision of this organ, the insect lost with it all sense of distance.