221 
anatomy of the mole-cricket. 
above one-fourth the size of the other pair ; they are of an 
oval form and convex externally ; and their nervures or 
wing-bones, as they are called by Dr. Leach, are remark- 
ably thick and hard. 
The under wings when expanded, measure full three 
inches from the outer extremity of one to the corresponding 
extremity of the other. They may be compared in form to 
a bivalve shell, contracted and elongated towards the hinge, 
at which point is the joint of the wing ; from hence, as many 
as thirty nervures, almost all of which are remarkably deli- 
cate, radiate in straight lines to every part of the extremity. 
A very thin and nearly colourless and transparent membrane 
forms the medium through which these nervures radiate ; 
and throughout the whole expanse of the wing, these ner- 
vures are mutually united by more delicate nervures, which 
cross at nearly regular intervals, and at right angles from 
one to the other, presenting altogether the appearance of a 
curiously checquered surface. These wings, though so broad 
when expanded, are scarcely the twelfth of an inch in breadth 
when folded ; and appear at first view, in this state, any 
thing but what they really are. They have indeed been often 
mistaken for a mere caudiform appendage to the other wings, 
from under which they emerge. When folded, and they 
fold themselves longitudinally like a fan, their very delicate 
texture is protected by the following simple contrivance. In 
each wing the two exterior longitudinal nervures, with their 
intervening membrane, are comparatively strong and thick ; 
and these form the lateral walls of the wings when folded. 
' In each wing also there^ are two other nervures not far 
from the former, and circumstanced like them with respect 
