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 hecomes the Filix 

 faemina 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 Linntean herl)aiium is marked Polypo- 

 diiim rhcetkum, and with the usual mark of authenticity attached to the spe- 

 cimen. 



4. Cystea dentata. 



This is the Polypodlum dentatum of Dickson, who first distinguished it 

 from fragUls. It was discovered by that acute and zealous botanist on Ben 

 Lawers, and afterwards by my late father on the C'lova 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 h-omfragilis. 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 oi fraglUs, 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, quae ad alas rotundioribus, omnibus autem 

 dentatis" of Seguier [J'eron. 3. p. 53. t. \.f. 2.) belong to dentata. 



5. CVSTEA REGIA. 



Dr. Hooker in his British Flora regards this and the alpina 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, 



3 l2 



