CHAPTER XXXVI. 



CYCADOPHYTA. 



The term Cycadophyta, suggested by Nathorst^, is used in 

 a comprehensive sense to include both recent Cycads and the 

 much larger number of extinct types which it is customary to 

 speak of as Cycadean plants or fossil Cycads. The designation 

 ' Cycads' in the case of the majority of the fossil forms is, however, 

 open to criticism on the ground that they differ too widely from 

 existing genera to be associated with them in one class. It would 

 be pedantic and inconvenient to give up the almost universal 

 practice of extending the term Cycad beyond the hmits defined 

 by the characters of recent species. The important point is to 

 adopt some classification which gives expression to our views as 

 to the degree of affinity between recent and extinct types. In a 

 considerable number of cases, especially impressions of presumably 

 Cycadean fronds and stems that occur without any fertile shoots, 

 it is impossible to determine the degree of relationship to modern 

 types. It was with a view to a rational group-designation for 

 such fossils that Nathorst proposed the term Cycadophyta, 

 including in it the two classes Cycadales and Bennettitales. The 

 Cycadales comprise the recent genera and such extinct types as 

 may legitimately be included in the same class, but as we shall 

 see later there are hardly any fossil species that can be assigned 

 to this section on thoroughly satisfactory grounds. The term 

 Bennettitales is used by Engler, Nathorst, and several other 

 authors as a class-designation for a large number of Mesozoic 

 Cycads agreeing in their more important morphological characters 

 with the Lower Cretaceous stems on which Carruthers^ founded 



' Nathorst (02) p. 3. '' Carruthera (70) p. 694. 



