160 Rhodora [Auowit 



more than one species mentioned, the first which conforms to the 

 requirements of the genus should be sufficient to hold it. A case in 

 point occurs in Athyrium, where in seven species mentioned by 

 Roth, only one (A. Filix-foemina), and that the sixth, conformed to 

 the requirements of the genus, yet that one is universally accepted 

 as the type for Athyrium, whether considered as an independent 

 genus, a sub-genus, or a mere section. 



As an example of how little the early authors thought about this 

 matter it may be stated that Presl, in his Tentamen Pteridographiae 

 after citing Schott for Aspidium named his own species (PlumUri) 

 first, although Schott had figured and cited A. trifoliatum for 

 Swartz's type. 



Here we have one of those illogical treatments where a name is 

 transferred from its original author to another merely because that 

 other reduces or enlarges its application. Schott illustrated Swartz's 

 Aspidium from a typical species, and although he himself cited 

 Swartz as authority, Presl subsequently cited him as authority. 

 Now if Presl was justified in citing Schott for Aspidium, subse- 

 quent authors would be justified in citing Aspidium, Presl, as 

 his treatment was different from Schott's. The common sense 

 view would therefore seem to be to anchor a generic name to its 

 original author whether its application be reduced or enlarged 

 as the right of an author to his own should remain intact. It is of 

 course to be expected that generic limitations should expand or con- 

 tract with the varying conditions of knowledge, and especially 

 through augmentation by additional species with slight deviations 

 form the original characters, but otherwise congeneric. 



This has been the case with Ncphrodium which was founded on 

 the character of the indusium, and apparently for the express purpose 

 of separating the kidney-shaped from the peltate form ; and no sub- 

 sequent treatment has destroyed the force of this one character for 

 which JVtp/irodium, Richard, stands to-day, exactly as it did more 

 than one hundred years ago. 



In tracing the further history of the genus down to the present 

 time we find that Swartz in 1806 (Synopsis Filicum) merged Nephro- 

 diuui into his Aspidium, where it is still retained by some of the very 

 best authorities. In 181 o Robert Brown published in his Prodromus 

 a list of New Holland ferns under Nephrodium, which he separated 

 from Aspidium, but without giving Richard credit for the genus as 



