Ch. XXIV.] FERNS OF CARBONIFEROUS PERIOD. 



361 



may perhaps be a fragment only of the entire flora, but they are enough 

 to show that the state of the vegetable world was then extremely different 

 from that now prevailing. We are struck at the first glance with the 

 similarity of many of the ferns to those now living, and the dissimilarity 



Fis. 464 



Fig. 465. 



Peeopteris lonchilica. 

 (Foss. Flo. 153.) 



a. Sphenopteris crenata. 



b. Part of the same, magnified. 



(Foss. Flo. 101.) 



of almost all the other fossils except the co- 

 niferae. Among the ferns, as in the case of 

 Pecopteris for example (fig. 464), it is not 

 always easy to decide whether they should 

 be referred to different genera from those 

 established for the classification of living 

 species ; whereas, in regard to most of the 

 other contemporary tribes, with the excep- 

 tion of the coniferae, it is often difficult to 

 guess the family, or even the class, to which 

 they belong. The ferns of the carboniferous 

 period are generally without organs of fruc- 

 tification, but in some specimens these are 

 well preserved. In the general absence of 

 such characters, they have been divided into 

 genera distinguished chiefly by the branching 

 of the fronds, and the way in which the veins of the leaves are disposed. 

 The larger portion are supposed to have been of the size of ordinary Eu- 

 ropean ferns, but some were decidedly arborescent, especially the group 



Caulapteris primceva, Lindley. 



