It is with no ordinary feeling- of satisfaction that tlic 

 Author has brought to a conclusion the five volumes consti- 

 tuting the 'Species Filicum' (accompanied by 304 plates, 

 representing 5,22 species), being descriptions of tlic known 

 Ferns, particularly of such as exist in the author's herbarium, 

 or are with sufficient accuracy described in works to which 

 he has had access. This title is further explained in the 

 preface to the first volume as including — 



1. Such species as the author has had the opportunity of 

 examining himself; 



2. Those which have been universally received, and which 

 his own observations have tended to prove are justly to be 

 regarded as distinct by references to satisfactory figures ; and 



3. A considerable number, of which he has neither seen 

 figures nor specimens, but which are given upon the authority 

 of botanists of name and character, though often imperfectly 

 characterized. 



It is just twenty years since the author commenced this la- 

 borious undertaking,* and during its progress his chief regret 

 has been that he has, especially in the earlier volumes, intro- 

 duced so many species merely on the ground of the name and 

 celebrity of the author, going as far back as Swartz (1806) and 

 Willdenow (1810), and which still remain in the category of 

 sjjecies non rite coynitoi. Of late years the number of bad or 

 dubious species has increased to a most alarming degree, con- 

 sequently increasing the difficulty of the tyro in determining 

 the good species ; so that we require to be more guarded 

 than ever in the selectionof what ought to be maintained and 

 what discarded. The excellent Dr. Grisebach has prefaced 

 his account of the genus Hymenophylhim, in his ' Flora of the 

 British West Indian Islands,' with the remark, " I omit se- 

 veral West Indian species of HymenopJiyllum and a few of 

 Trichomanes, named by Dr. Van den Bosch upo7i the same 



* The Work was issued in parts, and tlic/rVs/ volume in fonr parts was com- 

 pleted and issued January 1, 18 IG. 



