PLATE XXXVII. 



Alethopteris Seklii (Brongn.) Goepp. var. missouriensis D. W. 



(Page 117.) 



Fig. 1. Young pinna witli small pinnules. U. S. Nat. Mus., 3594. 

 la. Enlarged detail of pinnules of the same. X2. 

 2. Pinna with fully developed pinnules. U. S. Nat. Mus., 3594a. 



Alethopteris ambigua Lx. 



(Page 113.) 



Fig. 3. Young pinnas of this species. U. S. Nat. Mus., 5634. 

 3a. Detail showing young pinnules. X2. 

 i. Pinn* and pinnules showing the normal form and size. U. S. Nat. Mus., 3590. A pinnule of 

 the angustifoUa form of the Nenroptcris Scheuchzeri Hoffm. is seen on the left. 

 4o. Enlarged detail of pinnule of ^/e(/iOi)(em a»t%M(i. X2. 



384 



