Mr. Don’s Remarks on some British Ferns. 437 
segments of a dark green, and with the stipes and rhachis of a pale purple hue ; 
the other, and that the commonest, with the segments of a more delicate tex- 
ture, and the whole frond of a pale green. The latter variety varies much in 
size according to soil and situation ; in damp shady places it becomes the Filix 
femina of English Botany, and in more open exposed situations, the irriguum ; 
but neither of these states is entitled to be regarded as a distinct form. A 
specimen of the larger variety in the Linnæan herbarium is marked Polypo- 
dium rheticum, and with the usual mark of authenticity attached to the spe- 
cimen. 
4. CysTEA DENTATA. 
This is the Polypodium dentatum of Dickson, who first distinguished it 
from fragilis. It was discovered by that acute and zealous botanist on Ben 
Lawers, and afterwards by my late father on the Clova mountains. The plant 
appears to be peculiar to the Scottish alps, for after an attentive comparison 
of specimens from various stations, both in the Smithian herbarium and in that 
of my worthy friend Mr. Forster, I am satisfied that the Welsh plant is not dif- 
ferent from fragilis. 'The Scottish plant is distinguished by its broader, rounded 
pinnae, with short, blunt teeth, rather crenate than serrated, with the costae 
more conspicuous and flexuose. The indusium is much less divided at the 
margin, which character, if constant, will materially assist in distinguishing it 
from all the varieties of fragilis, among which, I fear, must be reckoned the 
angustata, as I can find no essential mark whereby to separate it. The figure 
in English Botany is altogether an indifferent one, with the stem and rhachis 
much too stout for any British species of this genus, and most probably belongs 
to fragilis, for it clearly does not represent the plant now under consideration. 
It is probable that the Aspidium tenue of Schkuhr (tab. 53. b. p.), and the 
* Filix non ramosa, alpina, foliolis, quce ad alas rotundioribus, omnibus autem 
dentatis" of Seguier (Veron. 3. p. 53, t. 1. f. 2.) belong to dentata. 
5. CysTEA REGIA. 
Dr. Hooker in his British Flora regards this and the a/pina as identically 
the same; but I cannot agree to this opinion of my learned friend, for the two 
plants appear to me to be essentially different. It is distinguished from alpina 
by its more compact frond, by its shorter, broader, and cuneiform segments, 
3L2 
