FILICES. 77 



* Sporangia borne on a reflexed portion of the margin of the 

 frond. 



VII. Adiantum L. Sori usually numerous and distinct. 

 Midrib of the pinnules near the lower margin or wanting. 



** Sporangia borne an a continuous vein-like receptacle "which 

 connects the apices of the veins. 



VIII. Pteris L. Sori continuous. Indusium delicate, 

 whitish. Midribs of pinnules central. 



*** Sporangia at or near the ends of unconnected veins, borne 

 on the under surface of the frond. 



IX. Cheilanthes Swz. Sori minute, at the ends of the 

 veins. Indusium continuous or interrupted. 



X. Cryptogramme R. Br. Sporangia on the back or 

 near the ends of the veins forming oblong or roundish sori, 

 which are at length confluent and cover the back of the pin- 

 nules. Sterile and fertile fronds unlike, smooth. 



XL Pellaea Link. Sori on the upper part of the veins, 

 distinct, or mostly forming a marginal band of sporangia. 

 Sterile and fertile fronds usually similar, smooth. 



TRIBE VI. CERATOPTERIDE^E. Sori on two or three 

 longitudinal veins which are nearly parallel with the edge of the 

 frond. Habits aquatic. 



XII. Ceratopteris Brong. The only genus ; having the 

 characters of the tribe. 



TRIBE VII. BLECHNE^E. Sori dorsal, linear or oblong, 

 borne on transverse veins, parallel to the midrib. Indusium 

 fixed at its outer margin, opening at the inner. 

 * Veins free. 



XIII. Lomaria Willd. Sori in a continuous band next 

 the midrib. Indusium elongate, formed of the recurved and 

 altered margin of the pinnae, or else sub-marginal. Fronds of 

 two sorts, elongate, pinnate. 



XIV. Blechnum L. Sori linear, elongate, continuous 

 near the midrib. Indusium continuous. Fronds pinnate. 



** Veins more or less reticulate. 



XV. Woodwardia Sm. Sori linear or oblong, forming 

 chain-like rows. Indusia separate. 



TRIBE VIII. ASPLENIE^E. Sori dorsal, linear or oblong, 



