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. Marattiacere. Exannulate. Ferns. 
„ III. Opliioglossaceae. Adder’s-tongue. Fern Ally. 
„ IV. Lycopodiacece. Lycopods. Fern A lly. 
„ Y. Marsileacese. Rhizocarps. Fern Ally 
The two first of these orders agree in having cir- 
cinate unfolding fronds, but differing essentially in 
habit and nature of their spore-cases; in the first, the 
spore-cases being membranous, and girded by an ar- 
ticulate ring, and the other firm and coriaceous, and 
destitute of a ring; they also differ in the nature of 
their roots, true Ferns having slender filiform, often 
soft, mossy roots, or they are hard and wiry, whereas in 
Marattiacece. they are thick and fleshy, indicating quite 
a distinct habit of growth from that of true Ferns. 
The third order, Ophioglossacece, seems to possess seme 
affinity to Marattiacece in the nature of its roots and 
spore- cases, but its straight vernation marks it as 
quite distinct. With Lycopodiacece it is connected 
