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96 exhibited by pupæ previous to the disclosure of the perfect insect will be afterwards given in the particular history of the Orders, to which we therefore refer. Imago or Perfect insect. When an insect quits its puparium, it is said to be complete or perfect, because it has then gone through all its changes, has all its parts fully matured and developed, and is capable of executing all the functions peculiar to its nature. The sexual distinctions, in particular, are now manifested, and the species become capable of continuing their kind. The wings are unfolded, and by their means they may almost be said to become inhabitants of a new element. It is now, in short, that, considered collectively, they exhibit in an especial manner all that diversity of form, peculiarity of structure, beauty and variety of colouring and ornament, as well as those singular instincts and modes of life for which the class is so remarkable. In considering the perfect insect in this place, we propose to give a view of its external and internal structure—in other words, of the exterior crust and organs as they appear to the eye, and of the internal parts as ascertained by dissection, or the anatomy properly so called. In so doing, we must necessarily render our account as general as possible, reserving the details of the modifications which the various parts undergo, till we come to treat of the separate orders; for it is, in fact, by these modifications that the various orders are constituted, and a review must, therefore, be taken of all the most important parts of structure as introductory to each, before it can be fully