Till 
INTRODUCTORY REMARKS. 
difficulty must attend any attempt to define species of 
Ferns. This is especially applicable in determining spe- 
cies from extensive suites of herbarium specimens. The 
number of species will be diminished or increased in ac- 
cordance with the botanist’s idea of specific differences : 
he will either amalgamate a number of allied forms under 
one specific name, or separate more or less of them as dis- 
tinct species. On inspecting living examples of allied 
forms, the latter view seems to claim adoption ; for although 
words often fail to convey the differences between indivi- 
duals, still the eye readily detects them, and knowing that 
each maintains its own peculiar phase or habit from year 
to year, the scientific observer considers himself justified 
in naming them distinct species. 
These observations briefly explain a few of the causes of 
the plurality of names possessed by most Ferns, also the 
difficulty of arriving at satisfactory conclusions respecting 
their generic and specific distinctions, affording little hope 
of an early unanimity amongst authors, and fully justify- 
ing every one who has studied Pteridology in giving his 
own views. 
J. Smith. 
Royal Botanic Gardens , 
KeWy June 1857. 
