37 



they are generally crowded, often much confused, and in maturity, 

 or rather on the dehiscence of the thecae, frequently become confluent 

 and cover the whole under surface. A tolerable notion of the posi- 

 tion of the indusium may be obtained from the enlarged view on 

 Tab. XIX., but it is difficult to portray its actual insertion and 

 mode of opening ; it is soon obliterated by the extension of the 

 sorus. 



So much difference of opinion exists regarding this normal 

 species of Cystopteris and its kindred species or varieties, and so 

 uncertain at present are our rules for specific distinction in this 

 tribe of plants, that it is with some diffidence I venture to adopt 

 even a very slight departure from the arrangement of my prede- 

 cessors ; but having cultivated them for nearly thirty years, and 

 observed them at intervals in their various native habitats for a 

 longer period, their present allotment is the result of an experience 

 to myself satisfactory, and the more so, because in the main point, 

 viz. the separation or rather retention of C. dentata as a species, 

 my decision is not a solitary one. 



In the Supplement to the 'English Botany/ Tab. 2790, a 

 figure of a fern, under the name of Cystopteris angustata, was 

 published, which, with its description, was evidently a mistake. 

 In the second edition of 'English Botany' (]841), this figure was 

 introduced, contrary to my expostulations regarding its incorrect- 

 ness, and the description in the text quoted from that of the Sup- 

 plement, with only one remark for which I am answerable " That 

 it (C. angustatd) is only a variety can scarcely be questioned, but 

 it is nearer C. fragilis than C. dentata." I am the more confirmed 

 in that opinion from later observation, and now introduce it as a 

 variety of the species before us : 



C. FRAGILIS, var. ANGUSTATA. TAB. XX. 



Frond oblong-lanceolate, bipinnate : pinnules linear-lanceolate, 

 more or less decurrent, acutely pinnatifid or toothed; ultimate 

 divisions narrow-oblong or linear. 



Cystopteris dentata, ft. Hooker, Brit. Fl. 



Found in similar situations to those in which C. fragilis grows, 

 and occasionally accompanying it, especially on the loose stone 

 f ences of North Wales and Cumberland. 



Few ferns are cultivated with greater facility than C. fragilis : 

 although growing more luxuriantly, and assuming its more graceful 

 aspect when planted in soil and situation corresponding to its 

 natural habitat, the ordinary garden mould, unless very adhesive, 

 is not ill adapted to its preservation. It may be grown in the 

 open border, forming, when not too fully exposed to the sun, 

 beautiful and elegant tufts that contrast well with the smaller 



