CONCLUSIONS. 241 



a distinct advance in the differentiation of reproductive structures 

 beyond the characteristic cycadean type. Were we in a position 

 to speak of the anatomical structure, or to describe more fully 

 the reproductive organs, of Wealden plants, it might be that we 

 should be able to recognize a distinct foreshadowing of angio- 

 spermous characters ; unfortunately, however, the extreme scarcity 

 of mineralized plant tissues precludes any such treatment of plant 

 types. In spite of the somewhat disappointing nature of the 

 flora from the point of view of angiosperm development, we 

 may reasonably hope that a more detailed comparison of floras 

 possessing a Wealden facies will enable us to add something of 

 value to the history of plant evolution, and to the facts of plant 

 distribution. 



