acted upon by other authors. But in the present state of our knowledge, a classification of this nature appears premature, there not being a sufficiency of facts and observations on which it can be satisfactorily founded.
The orders in which the larvæ have a strong resemblance to the perfect insect, are Hemiptera, Orthoptera, and certain genera of Neuroptera; in all the others, with a few exceptions, there is no resemblance between the two states.
In every instance insects may be considered as composed of thirteen segments, including the head, but in matured examples these are often merged in each other, owing to the disproportionate development of certain parts. In larvæ the mode of life, movements, &c. being more uniform, an enlargement of one segment is seldom made at the expense of another, and we accordingly find the normal number distinctly marked. They are most regular and uniform, however, in such as bear least resemblance to the winged insects they produce, although they can be traced without difficulty in nearly all other instances. The three segments immediately behind the head correspond respectively to the prothorax, mesothorax and metathorax of the perfect insect, and bear the three pair of legs (when these happen to exist,) which have been called the true legs, because they are persistent, to distinguish them from the abdominal or prolegs which are caducous and peculiar to the larvæ. The curious structure of the latter has
