COLEOPTERA. 
129 
burrowing in the wood. The larva was brought to the museum in a boot-tree, 
which its owner previously had in constant use for over fourteen years. Other 
cases are on record in which beetles have been seen fo emerge from furniture in 
houses, after having apparently passed an even more prolonged larval existence. 
Beetles, whether from the extent of their numbers or the variety of their 
shapes and instincts, are well qualified to play an important part in the economy 
of nature. Their chief function is that of universal scavengers. Not only do they 
dispose of the smaller quantities of dead and decaying animal and vegetable matter 
passed over by larger animals, but, by their own peculiar methods, they are enabled 
to attack and clear away even the carcases of quadrupeds of large size, and the 
dead trunks of the largest trees. Owing to the compactness of their shape, and 
the solidity of their outer covering, they are adapted for a much greater diversity 
in modes of life than is possible for insects of other orders. Besides groups fitted 
to act as scavengers, we find further series of forms that live in, and prey upon, 
all kinds of plant life. There are groups again, either of terrestrial, arboreal, or 
aquatic habits, which seek for, and prey upon living animals of the smaller kinds. 
Some beetles live within the depths of the darkest caverns; and in such cases, 
having no use for eyes, they are generally blind. Others are to be found dwelling 
as “ guests ” in the homes of the ants and termites. Although the beetles cannot 
boast of such a long line of ancestry as the cockroaches and other Orthoptera, yet 
their records go back to an early period in geological history. There is no certain 
evidence that they existed in Palaeozoic times, and their first appearance has not 
been traced farther back than the beginning of the Secondary epoch. The earliest 
undoubted fossil remains of Coleoptera occur in the Swiss Trias, and from this 
period onwards fossil beetles are to be met with in greater or less abundance in 
rocks of different ages. They are especially well preserved in amber; and from 
the Tertiary amber beds on the Baltic thousands of specimens have been collected. 
Of the beetles now existing, quite one hundred and thirty thousand different 
species have been described, and, considering the rate at which new species 
are being yearly added, it is probable that before the end of the century the 
number of named species will fall little short of one hundred and fifty thousand. 
SECTION PENTAMERA. 
Beetles in which all the tarsi are five-jointed. In this section there comes first 
a great tribe of beetles, which, on account of their carnivorous tastes and predaceous 
habits, are known as the Adephaga. Their whole organisation seems well adapted 
to enable them to capture and devour their prey, and it is in the modifications 
directed to this end that some of the chief distinguishing characters of the tribe are 
to be found. Their legs are fitted for speedy locomotion, and their jaws for the 
cutting and tearing operations to which they are usually applied. The mandibles 
are acutely pointed and have sharp cutting edges; and the inner lobes of the 
maxillae are hard and hooked at the end. The outer lobes of the maxillae are two- 
jointed and slender, and resemble palpi; which explains the fact that these beetles 
are often described as having three pairs of palpi. The antennae are usually 
simple, and never clubbed. The tribe is divided into the Geodephaga and 
Hydradephaga, one subtribe containing terrestrial, the other aquatic forms. 
VOL. vi .—9 
