108 
NATURAL HISTORY OR 
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 meanSj 
is rather of a soft consistence ; in numerous ex- 
amples, how r ever, 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 stigmatic 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 
m the act of flight, by presenting a broad and con- 
