EXPLANATION OF THE PLATES. 
PLATES XXXI, XXXII.—MARGINAL SHIELD FERN. Dryopteris margin- 
alis, Plate XXXI.—1. Young plant attached to prothallus. 2-8. Young 
leaves in different stages of development. Plate XXXII.—1z. Mature sterile 
leaf. 2. Fertile pinnule of mature leaf, x 24. 
