f the Amphibia we are reminded of the other
prominent representatives of land life at the time. Snails, spiders, and
myriapods crept over the ground or along the stalks of the trees, and a
vast population of insects filled the air. We find a few stray wings in
the Silurian, and a large number of wings and fragments in the Devonian,
but it is in the Coal-forest that we find the first great expansion of
insect life, with a considerable development of myriapods, spiders, and
scorpions. Food was enormously abundant, and the insect at least had no
rival in the air, for neither bird nor flying reptile had yet appeared.
Hence we find the same generous growth as amongst the Amphibia.
Large primitive "may-flies" had wings four or five inches long; great
locust-like creatures had fat bodies sometimes twenty inches in length,
and soared on wings of remarkable breadth, or crawled on their six long,
sprawling legs. More than a thousand species of insects, and nearly
a hundred species of spiders and fifty of myriapods, are found in the
remains of the Coal-forests.

From the evolutionary point of view these new classes are as obscure in
their origin, yet as manifestly undergoing evolution when they do
fully appear, as the earlier classes we have considered. All are of a
primitive and generalised character; that is to say, characters
which are to-day distributed among widely different groups were then
concentrated and mingled in one common ancestor, out of which the later
groups will develop. All belong to the lowest orders of their class. No
Hymenopters (ants, bees, and wasps) or Coleopters (beetles) are found
in the Coal-forest; and it will be many millions of years before the
graceful butterfly enlivens the landscapes of the earth. The early
insects nearly all belong to the lower orders of the Orthopters
(cockroaches, crickets, locusts, etc.) and Neuropters (dragon-flies,
may-flies, etc.). A few traces of Hemipters (now mainly represented by
the degenerate bugs) are found, but nine-tenths of the Carboniferous
insects belong to the lowest orders of their class, the Orthopters and
Neuropters. In fact, they are such primitive and generalised insects,
and so frequently mingle the characteristics of the two orders, that
one of the highest authorities, Scudder, groups them in a special
and extinct order, the Palmodictyoptera; though this view is not now
generally adopted. We shall find the higher orders of insects making
their appearance