227 
to which I have alluded, and to which I have given the name of Des- 
mobrya, is observable in a more numerous group of ferns, bearing the 
following characters:—The fronds form a terminal axis, either in a 
single alternate series, or in a fascicle forming a corona; each succeed- 
ing frond is produced on the interior side of the bases of the preceding 
fronds, the bases being united and adherent; by the successive evo- 
lution of fronds a progressing accessory stem or cormus is formed, 
which varies in being decumbent or erect, short or more or less elon- 
gated, often assuming the aspect of trees, or, creeping on or under the 
surface of the ground, forming cespitose tufts: in those species pro- 
ducing their fronds in a single series the developing axis sometimes 
elongates before the evident evolution of the fronds, which are then 
more or less distant from each other, and by this mode of growth 
forming a creeping or scandent caudex, which often assumes the cha- 
racter of a sarmentum, and then appears to agree with the mode of 
growth I have called Eremobrya, but it is readily distinguished by 
the epidermis and vascular structure of the stipes being continuous 
and united, forming part of the developing axis, and not being articu- | 
late as in Eremobrya. The various modifications of the structure ob- 
servable in the group Desmobrya often mark the limits of what I term 
natural genera. Desmobrya therefore includes part of the Ctenopte- 
ris, and the whole of the Phegopteris groups of Polypodium; also 
Gymnogramma, Goniopteris, Meniscium, and other genera of Poly- 
podiez; the whole of Pteridiez, Aspleniew, and, with a few excep- 
tions, Acrostichiex, Aspidiee, Dicksoniex, and Cyathezx. 
‘Tt have here stated the obvious characters observed on examining 
examples of the two modes of development; the differences become 
more evident on examining their internal structure. I cannot enter 
into details in this place, the present collection not affording sufficient 
materials, nor the work space, to enable me to state the changes in 
affinity that will become necessary in consequence of adopting this 
mode of arrangement. I will only further mention, that, although the 
two modes of growth are in general readily determined, yet in some 
cases, especially herbarium specimens, it is a more difficult task. 
The genus Woodsia is peculiar, on account of the stipes of the origi- 
nal species having an articulation at a distance above the axis of ver- 
nation; nevertheless, as the vernation is terminal, and the bases of 
the stipes adherent, Woodsia must be referred to Desmobrya.” 
It may be observed that the Flora of Panama is comparatively poor 
in ferns; but those who are acquainted with Mr. Smith’s catholic 
