APTEROUS INSIXTS. 267 



The Poduni leaps into the air by a mechanical 

 contrivance of another kind ; employing for this 

 purpose the tail, which is very long, and forked at 

 the end. In its ordinary state this organ is kept 

 folded under the abdomen, where it is concealed 

 in a groove. The pieces of which it is composed 

 are articulated together in such a manner as to 

 admit of their being rapidly unbent by the action 

 of its muscles, the whole mechanism conspiring to 

 produce the effect of a powerful spring, by which 

 the body is propelled forwards to a considerable 

 distance. In some species, this flexible tail has a 

 flattened form, for the purpose of enabling the 

 insect to leap from the surface of water, an action 

 which it performs with apparently as much ease 

 as if it sprung from a solid resisting plane. 



The Lepisma leaps by means of moveable appen- 

 dages, placed in a double row along the under 

 side of the body, and acting like springs. There 

 are eight pair of these members, corresponding 

 in situation and structure to the false feet of the 

 Crustacea, and, like them, terminating in jointed 

 filaments. 



The Julus and the Scolopendra, which compose 

 the family of the Myriapoda, so called from the 

 immense number of their feet, undergo, to a certain 

 extent, a kind of metamorphosis in the progress 

 of their developement. When first hatched, they 

 have often no feet whatever, and resemble the 

 simpler kinds of worms. Legs at length make their 

 appearance ; but they arise in succession, and it is 

 not until the later periods of their growth that 

 these animals acquire their full complement of 



