456 



G. R. Wieland — Origin of Dicotyls. 



relatively few forms known, no doubt the student of gross 

 morphology might very well content himself with the theory 

 that the Wielandiella and other Ptero%>hyllum,-\\k.Q leaf types 



Fig. 3. 



Fig. 3. Otozamites hespera Wieland. x 2/3. 



were largely metamorphosed into net-veined forms. And the 

 more especially might this be true because there is every grada- 

 tion from Nilssonias with strong tendency to pinnule fusion and 

 blade-like form into typical Pteropliyllums, and thence into 



