580 PTERIDOSPERMS, ETC. [CH. XXVII 



the base, as in Pecopteris, but the more acute origin, more 

 arched form, and more frequent dichotomy of the lateral veins 

 are features shared by Neuropteris. As a rule, Mesozoic sterile 

 fronds with straight or folded, entire or dentate pinnules are 

 of the Cladophlebis type : this genus is especially characteristic 

 of Rhaetic and Jurassic floras. Examples of Cladophlebis 

 pinnules are shown in figs. 256, 257 (pp. 340, 342). It is to 

 be regretted that authors do not make more use of the generic 

 name Cladophlebis in describing sterile fronds, instead of 

 following the misleading and unscientific practice of employing 

 such genera as Pteris, Asplenites, and others on wholly insuffi- 

 cient grounds. 



