126 



THE GEOLOGICAL HISTORY OF PLANTS. 



of fossil ferns, in which 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. 



Fig. 51. — Group of ooal-formation ferns. A, Odontopt^-ia sviouneata (Bun- 

 bury). B, NeuropterU cordata (Brongniart). o, Alethopteria Umemtica 

 (Brongniart). d, Dictj/opterie ohliqua (Buntury). e, jPhyllopterw an- 

 Ugua (Dawson), magnified ; e>, Natural size, r, Neuropteris eyehpte- 

 roidee (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 GyatJiacem, the OpJiioglossem, the Hy- 



