peculiar elongation and flattening of three or
more of the terminal antennal segments, so that the feeler seems to
end in a number of leaf-like plates, or small comb-teeth (fig. 26, b,
c). The wings are well developed for flight, and there is a tendency
in the group, especially among the males, towards an excessive
development of the mandibles or the presence of enormous, horn-like
processes on the head or pronotum. There are four malpighian tubes.
The larvae are furnished with large heads, powerful mandibles and
well-developed legs, but the body-segments are feebly chitinized, and
the tail-end is swollen. They feed in wood or spend an underground
life devouring roots or animal excrement.

The _Lucanidae_ or stag beetles (figs. 1 and 25) have the terminal
antennal segments pectinate, and so arranged that the comb-like part
of the feeler cannot be curled up, while the elytra completely cover
the abdomen. There are about 600 species in the family, the males
being usually larger than the females, and remarkable for the size of
their mandibles. In the same species, however, great variation occurs
in the development of the mandibles, and the breadth of the head
varies correspondingly, the smallest type of male being but little
different in appearance from the female. The larvae of _Lucanidae_
live within the wood of trees, and may take three or four years to
attain their full growth. The _Passalidae_ are a tropical family of
beetles generally considered to be intermediate between stag-beetles
and chafers, the enlarged segments of the feeler being capable of
close approximation.

The _Scarabaeidae_ or chafers are an enormous family of about 15,000
species. The plate-like segments of the feeler (fig. 26, b, c) can be
brought close together so as to form a club-like termination; usually
the hinder abdominal segments are not covered by the elytra. In this
family there is often a marked divergence between the sexes; the
terminal antennal segments are larger in the male than in the female,
and the males may carry large spinous processes on the head or
prothorax, or both. These structures were believed by C. Darwin to be
explicable by sexual selection. The larvae have the three pairs of
legs well developed, and the hinder abdominal segments swollen. Most
of the _Scarabaeidae_ are vegetable-feeders, but one section of the
family--represented in temperate count