356 STUDIES IN FOSSIL BOTANY 



on such negative evidence as this (which is not without 

 its value, if drawn from sufficiently numerous instances) 

 that Stur in 1883 based his exclusion of certain of 

 these genera from Ferns and their reference to Cycads. 

 Subsequently, a large body of well-ascertained positive 

 data accumulated, derived mainly from anatomical in- 

 vestigation, on which, indeed, we then had to depend, 

 for in none of the plants concerned were the organs 

 of reproduction known with certainty up to the year 

 1903. The anatomical characters observed indicated 

 a position intermediate, at least in certain respects, 

 between Ferns and Gymnosperms, the particular class 

 of Gymnosperms approached being that of the Cycado- 

 phyta. Hence the convenient name Cycadofilices was 

 applied by Professor Potonie to the group, and gener- 

 ally adopted. 



The remarkable progress made in the last four or 

 five years leaves no doubt that most, if not all, the 

 members of this intermediate group, which embraces the 

 majority of the Fern-like plants of the Palaeozoic, bore 

 seeds. They have thus proved to be much nearer Gym- 

 nosperms than appeared before, but on account of vege- 

 tative and other characters they retain an intermediate 

 position, and are now associated under the name Pterido- 

 spermeae. This class may be provisionally defined as : 



Plants resembling Ferns in habit and in many of 

 their anatomical characters, bearing seeds of a Cycadean 

 type ; seeds and microsporangia borne on fronds 

 only slightly modified as compared with the vegetative 

 leaves. 



The Pteridosperms were thus, as Van Tieghem has 

 said, " Phanerogams without flowers." 



