ROACHES AND OTHER ANCIENT INSECTS
The paleontological history of life on the earth shows us that the land has been inhabited successively by different forms of animals and plants. A particular group of creatures appears upon the scene, first in comparative insignificance; then it increases in numbers, in diversity of forms, and usually in the size of individuals, and may become the dominant form of life; then again it falls back to insignificance as its individuals decrease in size, its species in numbers, until perhaps its type becomes extinct. Meanwhile another group, representing another type of structure, comes into prominence, flourishes, and declines. It is a mistake, however, to get the impression that all forms of life have had this succession of up and down in their history, for there are many animals that have existed with little change for immense periods of time.
The history of insects gives us a good example of permanence. The insects must have begun to be insects somewhere in those remote periods of time before the earliest known records of animals were preserved in the rocks. They must have been present during the age when the water swarmed with sharks and great armored fishes; they certainly flourished during the era when our coal beds were being deposited; they saw the rise of the huge amphibians and the great reptilian beasts, the Dinosaurus, the Ichtyosaurus, the Plesiosaurus, the Mosasaurus, and all the test of that monster tribe whose names are now familiar household words and whose bones are to be seen in all our museums. The insects were branching out into new forms during the time when birds had teeth and were being evolved from their reptile ancestors, and when the flowering plants were beginning to decorate the landscape; they were present from the beginning of the age of mammals to its culmination in the great fur-bearing creatures but recently extinct; they attended the advent of man and have followed man's whole evolution to the present time; they are with us yet—a vigorous race that
[85]
