COLEOPTERA. 
203 
designed to take an active share in flight. That 
function being entirely devolved on the membranous 
wings, which receive their impulse from the muscles 
of the metathorax, that segment is proportion ably 
augmented, its dimensions frequently equalling those 
of the prothorax. 
These insects undergo a complete metamorphosis. 
In a few exceptional cases, notwithstanding, the 
larva bears a close resemblance to the imago, as, for 
example, in Drilus, the female glow-worm, and al- 
most the whole family of the Staphylinidse. In such 
an extensive order, the larvae are, of course, of very 
varied aspect ; commonly they are soft and pale, 
the head, and a few of the anterior segments alone 
being corneous. The absence of the brilliant colours 
which often distinguish the perfect insect, is to be 
attributed to their usually frequenting places where 
they are concealed from the light ; some living be- 
neath the ground, others in the stems of trees and 
herbaceous plants, putrescent fungi, decaying veget- 
able and animal matter, &c. In such situations long 
antennae would be an encumbrance to them, and 
these appendages accordingly are in all cases short 
and inconspicuous. Most of them possess six thoracic 
legs, without any auxiliary organs of motion, but not 
a few are entirely apodal, the only substitutes for 
legs being small warts or prominences. Such as are 
aquatic, effect their motions in the water merely by 
the action of the legs, aided probably in Gyrinus and 
Hydrophilus caraboides, by the plumose or fin-like 
branchiae placed along the sides of the body. The 
