88 FROM FISH TO PHILOSOPHER 



bergen. In this moist climate tree ferns, seed ferns, and 

 Other plants, very much alike all over the world, devel- 

 oped with unprecedented luxuriance. Characteristic of 

 the Coal Measures everywhere were the giant scouring 

 rushes— of which the diminutive horsetail, Equisetum, is 

 a himible descendant— growing to a height of 30 feet 

 and a diameter of 12 inches. The largest plants were 

 the 'scale trees,' the stumps of which attained a diameter 

 of four to six feet and the trunks a height of 100 feet. 

 Almost as large were the Cordaites, the forenmners of 

 modem conifers, and the only trees that to a modem 

 eye would look even superficially like trees; their leaves, 

 however, were blades and not needles, and their seeds 

 resembled bunches of grapes rather than pine cones. 

 (There were, as yet, no flowering plants, most of which 

 were not evolved imtil the Cenozoic era.) The roots of 

 this lush vegetation were immersed in standing water, 

 as in the present Florida Everglades and in the bayous 

 of the Mississippi River, and as the vegetation died it 

 sank below the surface, where it was protected from de- 

 cay, generation upon generation piling up until the coal 

 seams reached a depth of thirty-five to forty feet. 



The Pennsylvanian was probably the warmest period 

 associated with abimdant rainfall in the history of the 

 earth, and in this agreeable climate terrestrial animal life 

 also came into its own. Insects underwent rapid evolu- 

 tion and grew to enormous size: dragonflies had a wing- 

 spread of twenty-nine inches, and the cockroaches were 

 so big— three to four inches long— that the age has face- 

 tiously been called *the Age of Cockroaches,' though it 

 would be fairer to call it 'the Age of Insects' were it not 

 that it is already knovm as 'the Age of Coal.' Spiders, 

 twelve-inch centipedes, snails, and himdreds of species 

 of scorpions luxuriated in a bountiful nature and sup- 

 plied abundant food for the great Amphibia whose 

 tracks, but not whose bones, are preserved in the preced- 

 ing Mississippian record. 



