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214 in Blatta which may be regarded as representing them. The clypeus or shield is always distinct among the Orthoptera, (Plate VI. fig. 2, c.) In several families of this order, "the suture, uniting the shield with the upper part of the skull, is membranaceous; hence the lip and shield move simultaneously with the mandibles in mastication. This is a departure from the general law of nature, and its occurrence is well worth remarking; as the motion of the shield might induce an observer to suppose it the lip, which would consequently become a new and supernumerary elementary part."

Of the three segments composing the thorax, the prothorax is often very much developed, to such a degree indeed, that in a particular group of the old genus Gryllus it sometimes exceeds in size all the rest of the insect. The mesothorax is very inconspicuous in this order, for the reason, that the forewings do not take a very important share in flight, and the part which supports them therefore admits of diminution. It is scarcely observable, indeed, when the wings are closed, except in certain species of the Mantis tribe. The metathorax, which is seldom so much developed as the preceding sections in the generality of insects, here acquires considerable prominence, and in certain Phasmæ seems to have attained its maximum. The metamorphosis of orthopterous insects, is what