GENERA OF FERNS AND THEIR CLASSIFICATION. 69 



brought to a close after twenty years' arduous and 

 patient study. Another work has also been compiled 

 during the last few years : I allude to "Lowe's Ferns." 

 It consists of nine volumes, with 550 plates, containing 

 figures of about two-thirds of the species in cultivation, 

 with vague descriptions and many erroneous synonyms. 

 This is a remarkable work in its way, but devoid of scien- 

 tific merit ; the figures being the only part worthy of 

 notice ; many of them are good representations of 

 species all such I have quoted ; others are not to be 

 relied upon, and tend rather to mislead. 



In the following pages I have classified Ferns and 

 certain other Cryptogamic plants, called Fern allies, 

 under five orders, viz. : 



Order I. Filices. Annulate, or true Ferns. 

 II. Marattiacese. Exannulate. Ferns. 

 III. Ophioglossaceae. Adder's-tongue. Fern Ally. 

 IV. Lycopodiacese. Lycopods. Fern Ally. 

 V. Marsileaceae. Khizocarps. Fern Ally. 



The two first of these orders agree in having cir- 

 oinate unfolding fronds, but differing essentially in 

 liabit and nature of their spore-cases; in the first, the 

 spore-cases being membranous, and girded by an ar- 

 biculate ring, and the other firm and coriaceous, and 

 destitute of a ring; they also differ in the nature of 

 bheir roots, true Ferns having slender filiform, often 

 5oft, mossy roots, or they are hard and wiry, whereas in 

 Marattiacea?, they are thick and fleshy, indicating quite 

 i distinct habit of growth from that of true Ferns. 

 The third order, Ophioglossacece, seems to possess some 

 iffinity to Marattiacece in the nature of its roots and 

 spore -cases, but its straight vernation marks it as 

 }uite distinct. With Lycopodiacece it is connected 



