361 



Willdenow, * has attempted a careful revision of the genus, 

 so it is obvious, that although those characters were sufficient 

 to separate the new species from others already described, yet 

 they by no means avail to keep them distinct from the 

 many discovered since. Hence arises the almost impos- 

 sibility of determining what particular kinds were intended 

 by authors. Farther, they have evidently been described 

 without a sufficiently minute examination of the exact forms 

 of the leaves, and stipules, serratures, and texture of the 

 foliage ; without due attention having been paid to the mode 

 of growth and ramification (which often lead to characters 

 of gi'eat importance) ; without, in short, the same careful and 

 microscopic investigation that is required for studying the 

 Mosses, a family that may, in many respects, be said to be 

 allied to them. Thus, perhaps, in the present enumeration 

 we may have adopted, as new, many species that are already, 

 though not accurately, defined, but whose identity it is totally 

 out of our power to determine : while, on the contrary, there 

 are individuals which may, with equal justice, be referred to 

 several specific descriptions, on account of the vagueness of 

 their characters. We do not flatter ourselves that we 

 have avoided the faults of our predecessors; for these are, 

 to a certain extent, inseparable from the subject on which we 

 treat. We shall feel grateful for the correction of our 

 friends, and for any suggestions that may lead to a more 

 complete acquaintance with the tribe, and we shall spare no 

 pains to render our Filices Asiatics, and Species Filicum, as 

 perfect as circumstances will allow. 



Although in the present list we shall seek to consult a 



* The useful Prodromus of M. Desvaux, in the 6th vol. of the Annales de la 

 Societe Linneenne de Paris, ought perhaps to be reckoned an exception to this 

 statement : but although that author has added several new species, yet he 

 appears to have continued a great number of old ones, whose validity rests upon 

 very slight grounds; and on the other hand, for want of diagnosis, (or fuU 

 descriptions instead,) even those Lycopodia which are there first defined, cannot 

 always be determined with certainty. It is to be regretted, that M. Desvaux 

 has not yet given to the world a more full history of the Ferns, of which the 

 memoir in question was only designed to be the forerunner. 



