244 
COLEOPTERA. 
These beetles are somewhat flattened, the head large, the antennse 
moderately long ; in the commonest species the eyes are divided by a 
Fig. 139.—Lucanus lunifer, male. [I. M. N.] 
projecting ridge, producing a small upper and a large lower eye. The 
prothorax is large and smooth, the elytra is smooth and shining. The 
legs are long, the tibiae broadened, the tarsi long and conspicuous. 
The beetles live in decaying trees and the males fly at night. The 
function of the very large mandibles is not always apparent and it is 
not clear that they use them; there is great variation in the degree of 
their development and intermediates from those resembling females to 
those with fully developed mandibles are found. (See page 189.) 
