302 



INSECTA. 



act like firm cushions, adapted, by their elasticity, to give greater effect 

 to the spring which raises the insect from the ground. In the magni- 

 fied view of the tarsus of an Abyssinian Grasshopper (fig. 150, E) the 

 arrangement of these organs is well exhibited. 



(790.) The next modification in the structure of the legs is met with 

 in such species as burrow beneath the surface of the ground, of which 

 mode of progression the most remarkable example is seen in the Mole- 

 cricket (Oryllotalpa vulgaris) (fig. 151). In this creature, the anterior 



Fig. 151. 



Gryllotalpa vulgaris. 



segment of the thorax, whereunto the fore -legs are appended, is won- 

 derfully enlarged and of great strength, while the legs themselves are 

 equally remarkable for their enormous bulk and muscularity. The tibia 

 is excessively dilated, and terminates obliquely in four sharp and strong- 

 spines. The whole of the tarsus would, at a first glance, appear to be 

 wanting ; but on inspection it is found to consist of three joints placed 

 upon the inner side of the tibia, the first two being broad and tooth- 

 shaped, while the last piece is very small and armed with two hooks. 

 The direction and motion of these hands is outwards, thus enabling the 

 animal most effectually to remove the earth when it burrows ; and, by 

 the help of such powerful instruments, it is astonishing how rapidly it 

 buries itself*. 



(791.) Similar examples of adaptation in the mechanical structure of 

 the legs of insects might be multiplied indefinitely ; we shall, however, 



* Kirby and Spenrc, Introd. to Ent. volii. p.3G2. 



