58 TEENS : BEITISH AND FOREIGN. 



the credit of being the first to employ characters from 

 venation upon a large scale is due to Professor Presl, 

 who, in 1836, published his celebrated "Tentamen 

 Pteridographige," where he described one hundred and 

 fifteen genera of Polypodiaceas alone, in the characters 

 of all of which the venation holds the most prominent 

 place. Several years before seeing Presl' s "Tenta- 

 men," I had been engaged in working out, and had 

 completed, a treatise upon the same subject, which, 

 with a few necessary alterations in nomenclature, I 

 afterwards published.* My views for the most 

 coincided with those of Presl, but I had paid more 

 attention to forming natural groups and bringing 

 together species agreeing in their mode of growth, 

 and vegetative organs; for it appeared to me that 

 pteridologists did not give sufficient importance to 

 that point, and even now it is not taken into considera- 

 tion as much as it deserves to be. With the exception 

 of my own more recent efforts to obtain characters from 

 the mode of growth presently to be explained, the only 

 further suggestion of any importance remaining to be 

 noticed is that of M. Fee, who, in his work on the 

 Polypodiacece, introduced characters taken from the 

 form and structure of the sporangia, the number of 

 articulations in their rings, and the form of their spores. 

 The form of the sporangia, and direction of their rings, 

 had previously been adopted by Presl and myself for 

 distinguishing the main orders or sub-orders of Ferns, 

 and I, in common with all modern pteridologists, still 

 rely upon those organs for that purpose ; but I cannot 

 consent to their introduction into generic and specific 

 characters, as proposed by Fee. Even were the dif- 



* Hook. Journ. Bot., 1841. 



