142 On the British species of Polypodium. 



be certain of two species, Pteris aquilina, and Polypodium 

 vulgar e. 



I hear some of my readers telling me, that this must have 

 arisen from sheer stupidity on my part ; the point I will not 

 contest; but, as a collateral remark, I would observe, that 

 books intended for instruction, should really afford some in- 

 formation to the ardent enquirer, although he might be stu- 

 pid. I never recollect giving up an enquiry without satisfy- 

 ing myself: the step I therefore took was to avail myself of 

 the knowledge of my friends, and thus get my ferns named. — 

 When this was accomplished, I compared the specimens with 

 the descriptions, and made them out very well. 



I have now paid some attention to the specific characters, 

 as laid down by our best authors, and I feel inclined to doubt 

 whether the most distinctive have been seized on. It appears 

 that the manner in which a frond is cut or divided, constitutes 

 almost the sole ground of specific distinction. Now, as we 

 find the majority of specimens in a state of semicultivation, 

 that is, partaking more or less of the influence of the spade, 

 or plough and harrow, and nourished by an infinite variety of 

 soils and manures, this character is precisely equivalent to 

 that of colour, in the feathers of a domestic fowl. I am in- 

 clined to think that better, that is, more stable characters, ex- 

 ist in the coverings of the seed, in the root, and in the extreme 

 outline of the frond ; and further, I am inclined to believe, 

 and, being nothing of a botanist, I hazard the opinion with 

 much diffidence, that the cutting or dividing of the frond sel- 

 dom furnishes a higher distinctive character than that of a va- 

 riety. 



As to characters which serve for generic or specific divi- 

 sions, I much fear we shall never decide which is which. I 

 have elsewhere said, that a genus is a most artificial division. 

 A species is a collection of similar animals or plants, descend- 

 ing from one common stock or parentage ; a genus is a re-u- 

 nion of several such species. The limits of a species are 

 marked by the natural power of reproducing its kind, but the 

 Creator has set no mark on that collection or re-union of spe- 

 cies, which we denominate a genus ; but every writer on na- 

 tural history, possesses and exercises a perfectly arbitrary 

 power, as to the limits and contents of the genus which he 

 describes. Thus, suppose A, B, C, and D, to represent four 

 distinct and well-ascertained species, decidedly differing from 

 each other, yet possessing certain characters in common ; one 

 author will insist that they constitute a natural genus ; a se- 

 cond will point out a character before unobserved, and shew 

 that they should be divided thus, AB — CD ; a third will dis- 



