596 



I'lLICES. 



Lindssca. 



Davallia. 



Nephrodium. 



Aspidium. 



Cyathea. 



Alsophila. 



Sphaeropteris. 



Woodsia. 



Trichopteris. 



Polypodium etc. 



Asplenluui. 



Allantodia. 



Diplagium, 



Scolopendrium. 



Didyinochlaena. 



In Ophioglosse^e PI. CXXXI. Fig. Ila. the venation 

 is somewhat less perfect, there being scarcely any central vein, 

 and the appearance of lateral veins towards the base of the 

 leaf arising more from an elongation of the reticulations, than 

 from the actual presence of a distinct order of veins. 



The petiole is decurrent, or perhaps the axis of the spike 

 adheres to it, at any rate the disposition is curious, and 

 singular. 



The spike itself obviously represents an involute leaf, on 

 the outer side it is marked with the dorsal vein, on the inner 

 a line exists pointing out the margins of inflexion, both sur- 

 faces are stomatose. PI. CXVXI. Fig. II.,o. 



There are some grounds for suppposing, that were more 

 leaves developed in this genus, they would be pinnate \ since 

 this is the structure of the spike, consisting of linear alter- 

 nating involute leaflets, carrying the sori on the margins. 

 PI. CXXXI. Fig, YLJb. 



In this the development is inverse, shewing the composi- 

 tion ? 



The sporula occupy the whole of the walls of each cell, 

 which are compound, half and half, they are not striate ; nor is 

 the distinction of the two membranes evident, the outer is 

 membranous, they burst readily by the action of water, they 

 are reinform. 



In its frond, which is e9tomatose, it approaches to algae J 



