EXTERNAL AN ATOM Y OF INSECTS. 629 



closed areolets, except in the Costal Area, where they 

 are inconspicuous; in Dytiscus marginalis, indeed, and 

 Tenehrio Molitor one or two may be found, but in ge- 

 neral there are none. In many of this tribe the post- 

 costa, which terminates at the joint of the wing, becomes 

 recurrent, so as to form a hook, which perhaps repre- 

 sents the stigma, as in Dynastes a ; in Creophilus K., a 

 rove-beetle, there is no hook but a broad plate adja- 

 cent to the costa. In the Strepsiptera Order the neu- 

 ration is extremely simple, the nervures, except one 

 insulated one, diverging from the base of the wing b : 

 in this respect, as well as in the form of that organ, 

 an approach is made to the Orthoptera. In the Derma- 

 ptera this approach is still more evident ; in the common 

 earwig c , the diverging nervures become numerous; be- 

 tween each is an insulated one, taking its origin in the 

 middle of the wing, and running to the margin ; a little 

 nearer to the latter all the nervures are dilated into a 

 plate; those of the anal area are angular d , and the ex- 

 posed part of the costal is as hard as the elytra. The 

 neuration in the Orthoptera Order may be called radiate, 

 the longitudinal nervures for the most part diverging from 

 the base of the wing like rays: in some few instances c , 

 but not often, I believe, an insulated nervure intervenes 

 between each ; traversing or connecting nervures, cutting 

 the longitudinal ones in various directions, ornament these 

 wings with an infinity of areolets, causing them to resem- 

 ble fine gauze or beautiful lace or net-work ; very often 

 these areolets are quadrangular, sometimes rhomboidal, 



Ibid. o". b Plate II. Fig. 1. Comp. Linn. Trans. xi. 



t.ix.f. 1. c Plate X. Fig. 5. d Ibid. n; o-,p\ 



* Stoll Spectres, t. xviii./. 65. 



