314? MOTIONS OF INSECTS. 



to spring into the air and recover their standing. If 

 you examine the breast (pectus) of one of these insects, 

 you will observe between the base of the anterior pair 

 of legs a short and rather blunt process, the point of 

 which is towards the aflus. Opposite to this point, and 

 a little before the base of the intermediate legs, you will 

 discover in the after-breast (postpectus) a rather deep 

 cavity, in which the point is often sheathed. This sim- 

 ple apparatus is all that the insect wants to effect the 

 above purpose. When laid upon its back, in your hand 

 if you please, it will first bend back, so as to form a very 

 obtuse angle with each other, the head and trunk, and 

 abdomen and metathorax, by which motion the mucro 

 is quite liberated from its sheath ; and then bending 

 them in a contrary direction, the mucro enters it again, 

 and the former attitude being briskly and suddenly re- 

 sumed, the mucro flies out with a spring, and the insect 

 rising, sometimes an inch or two into the air, regains its 

 legs and moves off. The upper part of the body, by its 

 pressure against the plane of position, assists this mo- 

 tion, during which the legs are kept close to its under- 

 side. Cuvier, when he says that man and birds are the 

 only animals that can leap vertically a , seems to have 

 forgotten this leap of Elaters, which is generally verti- 

 cal, the trunk being vertically above the organ that pro- 

 duces the leap. 



Other insects again leap by means of the abdomen or 

 some organs attached to it. An apterous species be- 

 longing to the Ickneumonidtf, and to the genus Cryptus 

 takes long leaps by first bending its abdomen inwards, 

 as De Geer thinks, and then pushing it with force along 

 :; Anat. Comp. i. 498. 



