214 SYSTEMATIC ARRANGEMENT. 



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 memhranaceous ; 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 we] 

 worth remarking ; as the motion of the shield migh 

 induce an observer to suppose it the lip, which wouh 

 consequently become a new and supernumerary ele 

 mentary part/' * 



Of the three segments composing the thorax, the 

 prothorax is often very much developed, to such 

 degree indeed, that in a particular group of the olc 

 genus Gryllus it sometimes exceeds in size all the 

 rest of the insect. The mesothorax is very incon- 

 spicuous in this order, for the reason, that the fore 

 wings do not take a very important share in flight, am 

 the part which supports them therefore admits o 

 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 pro- 

 minence, and in certain Phasmse seems to have at- 

 tained its maximum. 



The metamorphosis of orthopterous insects, is wha 



* External Anat. of Ins. Ent. Mag. voL II. 65. 



