2G0 
SYSTEMATIC ARRANGEMENT. 
formed for sucking. We have already described the 
oral tube of Butterflies and Moths, the only tribes so 
provided to which we have had occasion to advert. 
Jn the others, it presents a very different appearance, 
and likewise performs functions to which it is not 
adapted in these. Considered in relation to this im- 
portant structural peculiarity, the Hemiptera would 
require to be associated with the other orders similarly 
distinguished; but an arrangement which assumes 
the organs of flight as its regulating principle, points 
out the situation now assigned to it as the most natu- 
ral and appropriate. 
These organs deviate still further from the wings 
of the Col eoptera than those of the order last described. 
The upper pair may be considered as divided into 
two parts ; the anterior portion stiff and corneous, 
resembling elytra, the terminal portion membranous 
and more or less transparent. Hence the name 
Hemiptera or half-wings, (from rjfim the half,) and 
also hemelytra, the latter used to designate the upper 
wings when spoken of by themselves. This struc- 
ture, however, must be looked upon as merely char- 
acterising certain typical species, for the deviations 
from it are numerous and important. The extent 
of the horny portion of the hemelytra is liable to 
great variation in different genera. In most instances, 
it occupies about a third part of the surface, some- 
times the half, (as in Lygaeus ,) at other times two- 
thirds, (in Alydus ,) and three-fourths in certain Re- 
duvii. Occasionally, it is so extensive as to reduce 
the membranous portion to a narrow band at the tip. 
