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 per- 

 manence. 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 Ichthyosaurus, the Plesiosaurus, the Mosasaurus, and 

 all the rest 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 land- 

 scape; 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 



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