HEMIPTERA. 
267 
(Ledra aurita ,) and, from the curious aspect they 
give to the Centroti, these insects are called in France 
petit 8 diables and demi-diables . It is the pro thorax 
that forms the large foliaceous expansion covering 
the whole upper surface of the Mcmbraces, an ex- 
traordinary structure to which we are unable to assign 
any use, and which, as has been remarked, seems 
created by nature only for the purpose of shewing her 
inexhaustible fecundity in varying animal forms. 
The metatliorax is sometimes of considerable size 
in the Heteroptera. The scutcllum is often so large 
as to form a very marked feature in the appearance 
of these insects, covering the whole of the surface of 
the abdomen, and protecting the wings like an elytron. 
On the other hand, it is minute in Cicada and the 
allied genera, and difficult to determine, presenting 
at times the form of a St. Andrew' ’s cross, and some- 
what forked posteriorly. In Fulgora it is triangular, 
while in Centrotus, Membracis, and some other genera, 
it is linear and transverse. 
The legs present numerous variations in different 
species, as will appear from the descriptions subse- 
quently given. These variations in the locomotive 
organs are rendered necessary by their diversified 
habits and modes of life. In such as inhabit waters 
they become adapted to oar the body through a resist- 
ing medium, and in those that prey on their fellows 
they undergo such a change as to be convertible into 
instruments of prehension. Even in those cases where 
they are entirely terrestrial and apparently of similar 
habits, the legs frequently differ both in their relative 
