` 
ON GENERA AND SPECIES. 67 
the stipes being continuous and intimately connected with 
the portion of the stem forming the internode between the 
fronds, from which they cannot be separated without lacera- 
tion. In these three modes of growth—that is, whether 
the fronds are produced in a fascicle, forming an erect or 
decumbent axis, or in a single series—the principle of at- 
tachment is identical, and there being no articulation, as in 
Eremobrya, the bases of the stipes are so united and become 
indurated, forming the solid portion of the stem. To this 
mode of growth I have given the term Desmobrya, and 
in the definitions of the genera the venation is termed 
adherent. 
: The various modifications of Desmobrya I have found 
useful as auxiliary characters in indicating natural genera, 
but there are exceptional cases of species of Lastrea and 
Nephrodiwm, with erect fasciculate vernation, not distinguish- 
able by the character of their fronds from other species of 
the same genera with decumbent uniserial vernation ; 
nevertheless the adoption of the vernation and the nature 
of the accrescent axis as part of the definition of genera is 
of much assistance in determining the relative affinities of 
. many genera. 
In general the difference between Eremobrya and Des- 
mobrya, as above described, is obvious, and there can be 
no doubt that the two modes of growth are specially dis- 
tinct, the plants being endowed with very different natures, . 
. the vital power and tenacity of life, and power of resisting ` 
drought being much stronger in Eremobrya than in Desmo- 
brya ; and it is not a little remarkable that so far as obser- 
Vations upon cultivated plants enable me to ascertain, the ` 
latter are much more freely reproduced from spores than ` 
the former. It is also worthy of notice that in the ` 
importation of Ferns from distant countries, those of ` x 
