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II 



12G 



TUE GEOLOGICAL HISTORY OF PLANTS. 



of fossil ferns, in wliich the fructification is for the most 

 part wanting, it is still more so, depending in great part 

 on the form and venation of the divisions of the fronds. 



Fio. 51. — Group of coal-formation ferns, a, Odontopteris suhcuneata (Bnu- 

 bury). B, Neuropteria cordata (Brongniart). c, Alethopteris lonc/dtica 

 (Brongrniart). d, Dicti/opteris obiiqud I Hunhury), e, Phyllopteris an- 

 tiqua (Dawson), magnified; e>, Natural size, f, H'europteris cyclopte- 

 roidea (Dawson). 



Of about eight families into which modern ferns are 

 divided, seven are found in a fossil state, and of these, 

 four at least, the Ci/aihacew, the OpMoglossecB, the Hy- 



