106 THE LIFE-STORY OF INSECTS [CH. 



of the main outlines of the life-story of insects in the 

 wide, evolutionary sense may thus fitly conclude this 

 book. 



In the first place we turn to the ' records' of 

 those rocks, in whose stratified layers 1 are entombed 

 remains, often fragmentary and obscure, of the 

 insects of past ages of the earth's history. Com- 

 pared with the thousands of extinct types of hard- 

 shelled marine animals, such as the Mollusca, fossil 

 insects are few, as could only be expected, seeing that 

 insects are terrestrial and aerial creatures with slight 

 chance of preservation in sediments formed under 

 water. Yet a number of insect remains are now 

 known to naturalists, who are, in this connection, 

 more particularly indebted to the researches of 

 S. H. Scudder (1885), C. Brongniart (1894), and 

 A. Handlirsch (1906). 



We are now considering insects from the stand- 

 point of their life-histories, and the individual life- 

 story of an insect of which we possess but a few 

 fragments of wings or body, entombed in a rock 

 formed possibly before the period of the Coal 

 Measures, can only be a matter of inference. Still 

 it may safely be inferred that when the structure 

 of these remains clearly indicates affinity to some 

 existing order or family, the life-history of the 

 extinct creature must have resembled, on the whole, 



1 See Table of Geological Systems, p. 123. 



