AS COMPARED WITH THAT OF THE PRESENT DAY. 



401 



there is but one which presents any obvious or recognizable close 

 relationship with an order now in existence. Such is that of the ferns. 

 These were not only undoubted ferns, such as we have now living, but 

 one of the many fossil genera included under this order is probably 

 identical with a living one, though none of the species comprised in it 

 are alive now. The genus here alluded to is Pecopteris (Fig. 1), the 

 fossil representative, if not congener, of the modern Pteris (Fig. 2). 



Fi«. 2. 



Pteris esculenta (New Zealand). 



It is not improbable that there are other genera of living ferns fossilized 

 in the shales of the coal formation, but if so they are not so well pre- 

 served, probably from not offering the facilities for petrifaction (in a 

 determinable condition) that Pecopteris does. The perfect state in 



