64 THE ENTOMOLOGIST. 
should be attended by those of circulation, and that both 
should be enclosed by those of support throughout their 
circuitous and manifold ramifications. In Endosteates the 
bones form a connected system adapted to the especial 
function of support, and the organs of respiration consist of 
a single and simple windpipe opening at its upper extremity 
into the throat, and terminating at its lower extremity in 
the lungs, where the air which it has received at the throat 
comes in contact with the blood, and receives the necessary 
oxygenation to ensure its life-supporting properties. In 
hexapods we may suppose the same process of oxygenation 
necessary, but it does not take place at any fixed point, as 
the lungs: the process goes on in every part of the trunk, in 
the legs, wings, and antenne, because the windpipe is infi- 
nitely divided, and accompanies the blood-vessel in all its 
windings, however intricate, however ramified; so that the 
blood is always Jubricating and moistening the windpipe, 
and thus maintaining it in that condition so essential to the 
due performance of its functions. 
In both Endosteates and Exosteates the windpipe is com- 
posed of a series of rings closely appressed together ; they are 
sufficiently strong to maintain their form and position against 
any pressure that may come from without, but still suffi- 
ciently flexible to offer no impediment to the free motion of 
the equally flexible bones, which they invariably traverse 
from end to end. We have lately heard a good deal of 
flexible glass: these tubular bones, through which the 
blood and air constantly circulate, may be compared to 
flexible glass. ‘They also resemble glass in being frequently 
transparent, so that the functions, in course of progress 
within, may be observed and watched from without. This 
transparency, however, is confined to a few families, and, in 
these families, exclusively to the wing-bones; the existence 
of transparent bone in the trunk has not been noticed, and 
probably does not exist. Moreover, the wing-bones of 
Coleoptera are almost invariably opaque, and of a dark 
brown colour, which effectually precludes all examination 
of the interior. 
This differentiation of the two great provinces of animals 
—I say two, because 1 make no attempt to cope with the 
other two, Anosteate and Actiniate—is so totally, so diame- 
