EXPLANATION OF THE PLATES. 

 Plates XXXI, XXXII. — Marginal Shield Fern. Dryopteris margin- 

 alis. Plate XXXI. — i. Young plant attached to prothallus. 2-8. Young 

 leaves in difierent stages of development. Plate XXXII. — i. Mature sterile 

 leaf. 2. Fertile pinnule of mature leaf, X 2 J. 



