EXPLANATION OF THE PLATES. 



Plates XXVIII-XXX. — Massachusetts Fern. Dryopteris simulata. 

 Plate XXVIII. — I, 3-7. Young leaves in different stages of development. 2. 

 Very young plant. Plate XXIX. — 8. Young leaf in later stage of development. 

 Plate XXX. — I. Mature sterile leaf. 2. Section of fertile pinna of mature 

 leaf, X 2J. 



