of Lycopodium clavatum, L. 297 
species given by Bruchmann in his recent work has rendered 
this more possible : but it will be evident that all that can be 
done at present is to estimate the direction in which the facts 
appear to point ; further investigation both of the sporophyte 
and the gametophyte is needed before definite conclusions 
can be drawn. 
A natural classification of the Bryophyta and Pteridophyta, 
in which both sexual and asexual generations attain consider- 
able complexity and more or less complete physiological 
independence, must present special difficulty. The characters 
of both generations must be taken into account in ascertaining 
affinities ; and in both, recent adaptations to the conditions of 
life must be distinguished from long-inherited characters 
which indicate common descent and the degree of relationship. 
While the chances of error are increased, however, the 
additional evidence available in the case of those plants, 
neither generation of which is rudimentary or extremely 
reduced, cannot be neglected. In the Pteridophytes the 
classification has been founded almost entirely on the 
characters of the highly developed sporophyte, the differences 
in the sexual generation affording additional evidence in the 
recognition of the larger subdivisions. The resulting arrange- 
ment would in most cases be little affected by taking the 
characters of the gametophyte further into account, mainly 
because the latter exhibits such ready adaptability to its 
environment ; while those of its characters which may be 
regarded as of morphological importance, are for the most 
part closely similar throughout the large groups. 
The genus Lycopodium appears, however, to be to some 
extent exceptional among Vascular Cryptogams, since in it 
the sporophyte conforms closely to a general type, while great 
differences exist among the gametophytes. Thus the possible 
use of the characters of the sexual generation in arranging 
the species of this genus cannot be overlooked. The 
examination of an arrangement of the species of Lycopodium 
based on the external characters of the sporophyte, such as 
that given in Baker’s Fern-Allies, shows clearly that some 
