306 THE MECHANICAL FUNCTIONS. 



throw it upwards ; for it frequently falls from a 

 considerable height.* If the elater should fail in 

 its first [attempts to recover its feet, it repeats its 

 leaps till it succeeds. We find no example of a 

 similar structure in any other part of the animal 

 kingdom. 



The express adaptation of structure to the mode 

 of life designed for each species of insect is nowhere 

 more strongly marked than in those which are in- 

 tended to burrow in the earth : and of these the 

 Giyllo-talpa^ or mole cricket, presents a remarkable 

 example. A minute account of the anatomy of this 

 insect has been given by Dr. Kidd,t from which it 

 appears that being destined, like the mole, to live 

 beneath the surface of the earth, and to excavate 

 for itself a passage through the soil, it is furnished 

 with limbs peculiarly calculated for burrowing ; 

 vi^ith a skin which, being covered with a fine down, 

 effectually prevents the adhesion of the moist earth 

 through which it moves ; and with a form of body 

 enabling it to penetrate with least resistance the 

 opposing medium. By being endowed with the 

 power of moving as easily in a backward as in a 

 forward direction, it is enabled quickly to retreat 

 in the narrow channel it has excavated ; and as a 

 safeguard in these retrograde movements, it is pro- 

 vided with a pair of posterior appendages, which 

 are supplied with large nerves, and may be regarded 

 as serving the purpose of caudal antennae. 



The fore-legs, (one of which is represented in 



* See Biirmeister's Manual of Entomology, by Shuckard, § 269. 

 He regards the spine as merely regulating the direction, but giving 

 no elastic force to the movements. 



t Phil. Trans, for 1825, p. 203. 



Vi 



