INSECTS 



shows no sign of weakening or of decrease in numbers. 

 Of all the land animals, the insects are the true blue-blood 

 aristocrats by length of pedigree. 



The first remains of insects known are found in the 

 upper beds of the rocks laid down in the geological period 

 of the earth's history known as the Carboniferous. Dur- 



Fig. 54. A group of common Carboniferous plants reaching the size and pro- 

 portions of large trees. (From Chamberlin and Salisbury, drawn by Mildred 

 Marvin from restorations of fossil specimens.) Courtesy of Henry Holt & Co. 

 Of the two large trees in the foreground, the one on the left is a Sigillaria, that 

 on the right a Lepidodendron; of the two large central trees in the background 

 the left :3 a Cordaite's, the right a tree fern; the tall stalks in the outermost circle 

 are Calamites, plants related to our horsetail ferns 



ing Carboniferous times much of the land along the 

 shores of inland seas or lakes was marshy and supported 

 great forests from which our coal deposits have been 

 formed. But the Carboniferous landscape would have 

 had a strange and curious look to us, accustomed as we 



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