ON GENERA AND SPECIES. 75 



described for the first time. To avoid this I have as far as 

 possible followed the plan adopted in my " Arrangement 

 of Ferns," in 1841, where I have said that " The authority 

 for the specific names being in a parenthesis denotes that 

 such species stood formerly under one or other of the 

 genera given as synonyms." 



I have to add that on account of the gradual failure oi 

 my sig-ht I have not been able to determine the position of 

 certain species. I therefore direct the special attention of 

 those who adopt my mode of classification, to the mass 

 of species included under the section Enpolypodium of the 

 " Species Filicum," of which the author says the stipes are 

 " articulated upon the caudex, as appears to be all of this 

 group," of which there are 151 described. I have, how- 

 ever, failed to identify more than fifty of the species as 

 having articulate vernation, and which 1 place under Poly- 

 podium as restricted by me, and as far as I have been able 

 to determine the many species represented by P. trichoma- 

 noides, P. moniliforme, and P. peruviana, have adherent 

 vernation, and which I refer to the genas Glenopteris in 

 Desmobrya. I also direct special attention to the arboroid 

 species of Phegopteris, Laslrea, Goniopteris, and Nephrodium, 

 which, on account of their special habit, and the pinnas 

 being articulate with the rachis appears to me of sufficient 

 importance to warrant their separation from the more 

 humble species of their respective genera. 



The extensive genus Maphoglosstim also presents great 

 difierence in the nature of its vernation, which appears to 

 ha of sufficient importance to justify the species being 

 arranged in separate generic groups. 



I conclude my general observations on the classification 

 uf Ferns by saying that my views, like those of other 

 ^^'riters, are open to criticism. If the critics have studied 



