CHAPTER III. 



DISTRIBUTION AND NOMENCLATURE OF FERNS. 



|T page 128 of Dana's "Manual of Geolo- 

 gy " is a very simple diagram, which well 

 illustrates the antiquity, development, and 

 comparative abundance of ferns in the geologic 

 periods of the earth. As that will teach us, ferns 

 are first found in the Devonian, or Age of Fishes. 

 Their number increases rapidly from that time, 

 until, in the Carboniferous Period, they reach 

 their highest point in structure, quantity, and size. 

 In the epochs which follow they are slowly re- 

 duced in number, until the Age of Man, when we 

 find them as they are now, with no apparent 

 change since prehistoric days. From what this 

 record shows us, we are led to look at the condi- 

 tions under which ferns attained their greatest 

 perfection. According to Dana, these were "a 

 moist, warm climate," with " less sunshine," since 

 there " was a very much larger evaporation than 

 now ;" "a climate insular throughout," with 



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