* the finest in cultivation,” it in 1864 consisted of nearly 
one-half of the number of the species described by him in. 
that work, but of these the learned author made less use 
than might have been expected. This was consequent on 
finding a considerable difference in describing species from 
living plants and herbarium specimens; for in many cases 
it was found that it was not till specimens of the cultivated 
plants were dried that they could be identified with native - 
. Specimens of the same supposed species in the herbarium ; 
consequently the descriptions in the “Species Filicum " 
are, with few exceptions, entirely founded: on specimens in 
the author's herbarium. 
With me it was otherwise: the living collection re- 
. quiring daily care and attention, led me to become 
acquainted with the special habits and modes of growth of 
_ the different species; and this has enabled me draw up the 
following natural arrangement. I say natural, but it must 
. be understood that any sequence of allied genera has its — 
limit, and that it is only in individual tribes that genera, 
in most cases, can be so arranged as to form natural 
transitions from one to another. By this several tribes 
become naturally connected, while others, such as Aspleniee, 
Hymenophyllew, and Gleicheniee, may be called independent 
tribes, 
The principle of the following arrangement is based on 
the different modes of vernation and habit. It begins 
with the division Eremobrya, followed by Desmobrya and 
of which there are twenty-nine in all; each tribe contains | 
agreater or lesser number of genera, and the genera of 
characters are arranged under sections. The characters of ` 
each Bees are given, ge, with the nature of the ` ` 
X por 
ON GENERA AND SPECIES. 79 
Seaphobrya ; ; each of these divisions are divided into tribes, e m 
each tribe when possessing any well marked differential ut 
