108 NATURAL HISTORY OP 



horny substance, similar to the crustaceous envelope 

 of the head and thorax, and in the language of en- 

 tomology are named elytra or wing-cases. These 

 organs are likewise articulated to the thorax, and 

 when at rest lie along the back of the abdomen, in 

 the middle of which their internal edges meet and 

 form a straight longitudinal line or suture. At this 

 point of junction the wing-cases are sometimes sol- 

 dered together, and form a single undivided piece, 

 which completely incases the abdomen. In such 

 instances the inferior wings are wanting, or exist in 

 a very rudimentary condition, and the species are 

 of course incapable of flight. The elytra usually 

 cover the whole upper surface of the abdomen,, 

 which, being sufficiently protected by their means ; 

 is rather of a soft consistence ; in numerous ex^ 

 amples, however, they cover only a small portion at 

 its base, in which case the exposed surface is equally 

 rigid with the rest of the body. Without some 

 protection similar to that afforded by the elytra, the 

 inferior wings would be continually liable to injury, 

 as they are but little adapted by their delicate tex- 

 ture to resist the attrition to which they are so often 

 exposed by the haunts ot the species, many of which 

 live among loose earth and under stones. The wing- 

 cases likewise serve to protect the stlgmatic open- 

 ings, placed along the sides of the abdomen, by 

 which air is introduced for the purposes of respira- 

 tion ; and it is probable that they assist materially 

 in the act of flight, by presenting a broad and con- 



