COLEOPTERA. 203 



I 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 proportionably 



| augmented, its dimensions frequently equalling those 



j of the prothorax. 



These insects undergo a complete metamorphosis. 



J 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 Staphylinidae. 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 



