PTEROPSIDA 115 



a matter of personal preference. Accordingly, there are 

 almost as many different ways of classifying the group as 

 there are textbooks dealing with it, and this is particularly 

 true of the fossil members of the group. 



At this point, only the major subdivisions are presented, 

 the details being deferred until each subgroup is dealt with. 



A Primofilices* 



1 Cladoxylales* 



2 Coenopteridales* 



B Eusporangiatae 



1 Marattiales 



2 Ophioglossales 



C Osmundidae 

 Osmundales 



D Leptosporangiatae 



1 Filicales 



2 Marsileales 



3 Salviniales 



Primofilices 



This is a remarkable group of plants that first appeared in 

 the Middle Devonian and survived until the end of the 

 Palaeozoic. As the name suggests, they were probably the 

 ancestors of modern ferns. They may be classified as follows : 



1 Cladoxylales* 



Cladoxylaceae* Cladoxylon* (Hierogramma, 



Syncardia, Clepsydropsis) 

 Pseudosporochnaceae * Pseudosporochnus* 



2 Coenopteridales* 



Zygopteridaceae* Austroclepis'^ , Metaclepsydropsis*, 



Diplolabis* Dineuron* 

 Rhacophyton* Ankyropteris,* 

 Etapteris* { = Zygopteris, 

 = Botrychioxylon) Tubicaulis* 



