INTRODUCTION. 
A Fern is a flowerless plant which has a fibrous root, vascular stem, 
nerved leaves, reticulated cuticle furnished with stomata ; and which 
bears spores as fruit in capsular receptacles. 
The Ferns and their Allies form the first order of the Linnsean 
class Cryptogamia, and the structure of them shows so exactly an 
intermediate character between the Vasculares and Cellulares, that 
all systems of classification have assigned them this station among 
vegetables. They are without flowers, have but imperfectly-formed 
vessels, and no deposition of real woody fibre, they therefore cannot 
with propriety he arranged with Phsenogamous plants ; while their 
semi-vascular texture and fully- developed leaves show their organi- 
zation to be greatly above that of any other order of Cryptogamia. 
Although the True Ferns have a direct analogy with the Palmse 
and Cycadese, the connexion between them and other orders is more 
apparent in the Pteroides or Fern Allies, particularly the Equiseta 
and Lycopodia. The Equiseta are nearly connected with several 
orders of Flowering plants. In their hollow, jointed, silicious stems, 
they resemble the Grasses ; in other respects the Coniferse and 
Amentacese, approaching the one by means of the genus Casuarina, 
and the other by that of Ephedra, nor are they far removed in 
structure from the Charas; thus connecting also the Ferns and the 
Algse. The other of the Fern Allies, the Lycopodia, were considered 
by the earlier botanists as Mosses, so slightly do they differ from that 
tribe, not only in habit, but in many important characteristics. 
Thus the tribes under consideration, which are divided according to 
the modern system into Filicales, Lycopodales, and Equisetales; 
the first the True Ferns, the others the Pteroids or Fern Allies, 
altogether form valuable, because well-connecting links in the great 
chain of nature. 
B 
