SPRING-TAILS. 627 



the Gry'((ina, appear to frequent trees and shrubs more 

 than the other tribes, the members of which generally 

 keep among herbage ; and, in accordance with this habit, 

 many of the exotic species have wing-cases which present 

 the most perfect resemblance to leaves both in colour and 

 venation. Of the Achetina, the common Cricket (Acheta 

 domestica), fig. 285, the noisy little denizen of the kitchen- 

 hearth, is the best example. Thesp. insects have the 

 antennae slender and tapering, and often considerably 

 .onger than the body. They agree with the Gryllina in 

 the structure of their singing apparatus ; but the wings, 

 instead of being arranged in the form of a high-pitched 

 70of, are laid fiat upon the back. Some of them possess 

 ocelli, whilst others are destitute of those organs. The 

 wings are very long, and folded up in such a manner as 

 to project beyond the wing-cases in the form of a pair of 

 tapering tails ; the abdomen is also furnished, in both 

 sexes, with a pair of pilose, bristle-shaped, caudal appen- 

 dages : in the female these form a long slender ovipositor, 

 the two filaments being placed side by side, and somewhat 

 thickened at the tip. The tarsi are three-jointed. The 

 horny covering and muscular apparatus under the wing- 

 cases of the Cricket 

 are very curious, and 

 will repay microscopi- 

 cal examination. The 



Cricket has two wings, Fi 8- 2g 5. —The Cricket. 



covered by elytra or wing-cases of a dry membranous consis- 

 tency, near the base of which is a horny ridge having trans- 

 verse furrows, exactly resembling a rasp or file ; this it rubs 

 against its body with a very brisk motion, and produces 

 the well-known merry chirp ; the intensity of which is 

 increased by a hollow space, called the tympanum, acting 

 as a sounding-board. The gastric teeth are numerous. 



In Thysamira there is a remarkable diversity of struc- 

 ture ; they undergo no metamorphosis, and have no wings. 

 This order contains two families, Spring-tails, Poduridas, 

 and Lepismence. In the former, the caudal appendage 

 has the form of a forked tail (Podura, fig. 286), which is 

 bent under the body when not in use ; by its sudden ex- 

 tortion the insect causes itself to spring to a very great 



ss 2 



