70 FERNS : BEITISH AND FOKEIGN. 



through Pliylloglossum Drummondii, a singular little 

 plant, having the appearance of a small plant of Ophio- 

 glossum Lusitanicum, but with a spike formed of small 

 bracts containing sporangia in their axis, analogous to 

 Lycopodiacece ; otherwise the family of I/ycopods stands 

 quite isolated, appearing to have no very evident 

 transition forms connecting it with any other except 

 the extinct order Lepidodendrece : the same may be 

 said of the last order, Marsileacece. 



The most important of the above orders is Filiees. 

 Sir W. J. Hooker, in the " Species Filicum," describes 

 two thousand five hundred species of annulate Ferns, 

 which, with those described since the first publica- 

 tion of that work, twenty years ago, may now be 

 considered to amount to no fewer than three thou- 

 sand. To arrange and classify this mass of species is 

 no easy task. The chief writers on Ferns adopt the 

 difference in the position and direction of the ring, as 

 the first important character for subdividing the order. 

 This, however, divides it very unequally, the greater 

 mass having the ring of the spore-case vertical, which 

 characterizes the sub-order Polypodiacece ; this I have 

 in the following arrangement subdivided into eleven 

 tribes, as follows : 



CONSPECTUS OF ARRANGEMENT OF ORDERS, SUB-ORDERS, 

 AND TRIBES. 





. Sporangia furnished with an articulate elastic ring. 

 ORDER I. Filiccs. 



Frond circinately unfolding. Sporangia furnished with vertical, 

 horizontal, or sub-oblique ring. 



Sub-Order I. Polypodiacece. 

 Ring vertical 



