39 



the termination of the veins, have a disposition almost marginal, 

 and indeed, where numerous and becoming confluent, as they 

 usually do in maturity, form a complete and striking border to the 

 under surface of the pinnules, very different to those of C. fragilis 

 and C. angustata. The rachis is very slender, smooth, and almost 

 universally of a deep brownish-purple hue. 



The variety C.Dickie 'ana ,Tab. XXI I. , is a very marked and peculiar 

 one, apparently retaining its distinguishing characters under culti- 

 vation. The general outline of the frond is ovate-lanceolate, and 

 all of its divisions are broader and more rounded than those of the 

 normal C. dentata; they are likewise nearer together, and their 

 greater breadth occasions an overlapping of each other, that, added 

 to the more decided tendency to horizontality of the pinnae, give it 

 at first sight the aspect of a distinct species. A close comparison, 

 however, with the latter plant soon dispels the illusion. The 

 pinnae and pinnules are often more or less confluent, instead of 

 being quite distinct, thus departing from the bipinnate character. 

 The sori are never confluent in maturity, but have the intromarginal 

 position. Mr. Newman remarks, on the authority of Mr. Wol- 

 laston, that the spores of C. frayilis " are always echinate, those of 

 Dickieana simply verrucate"; the latter is the case with those of 

 C. dentata, but whether a constant character of that species I am 

 not prepared to assert. 



This remarkable variety was found by Dr. Dickie in 1846, 

 growing in a cave by the sea near Aberdeen, and has not hitherto 

 been met with elsewhere. 



Whether the arrangement of the four allied forms of the genus 

 here adopted or proposed be correct or otherwise is of little import- 

 ance ; under either circumstance the two named as species, and 

 which I have always considered as such, will be useful as rallying- 

 points to those who may feel inclined to discuss the subject. Mr. 

 Moore, who has placed all the four as varieties of C. fragilis, re- 

 marks : " I am inclined to think C. dentata to be sufficiently 

 distinct to take rank as a species, and to look upon C. Dickieana 

 as an extreme form of it." Mr. Newman, on the contrary, ob- 

 serves : " My own judgment, improved, but by no means matured, 

 by the observations of sixteen years, regards dentata as a nonentity, 

 angustata as a synonym of that nonentity, and Dickieana as a 

 possible, but by no means established species." Farther on, he 

 adds : " The propriety of separating Dickieana from fragilis rests 

 on these grounds, it is a perfectly healthy plant, not monstrous 

 or distorted, and produced freely from seed, becoming a perfect 

 weed ; whereas fragilis, under similar treatment, rarely reproduces 

 itself. Cultivated in the same soil and in the same pot with 

 fragilis, the latter becomes larger and more vigorous, Dickieana 

 smaller and less vigorous : and the more care the cultivator be- 



