EXPLANATION OF THE PLATES. 
Pirates XLII-XLV.—SENSITIVE FERN. Onoclea sensibilis. Plate XLII. 
—1. Young plant attached to prothallus. 2-6. Young leaves in early stages 
of development. Plate XLIII.—Young leaf in later stage of development. 
Plate XLIV.—1. Mature fertile leaf. 2. Mature sterile leaf. 3. Section of 
pinna of fertileleaf, X 2}. 4. Section of pinna of sterile leaf, X 23. Plate 
XLV.—Leaves intermediate between the mature sterile and fertile leaves. 
