IOWA PTERIDOPHYTA. 149 



working systematists of the world. Anything approaching 

 stability of nomenclature is out of question until these 

 codes are reduced to one. 



The difficulties which result from the condition of affairs 

 above set forth are well illustrated in a number of 

 cases. Thus Phegopteris dryoptcris (L.) Fee was described 

 as Polypodium dryoptcris by Iyinne. In 1803 Michaux* 

 referred it to the genus Ncplirodium , and recently Diels 

 restored the namef. In 1850-1852 Fee established the 

 genus Phegopteris to which our species was referred. Up 

 to this point, then, the synonymy would stand as follows: 



Polypodium dryoptcris L,. 



Ncplirodium dryoptcris Michaux. 



Phegopteris dryoptcris (X.) Fee. 



Ncplirodium dryoptcris (L.) Mx. (restored). 



But O. Kuntze refers Ncplirodium to Dryoptcris, and if 

 Diels' view of genera and Kuntze 's nomenclature be 

 adopted the name would stand as Dryoptcris dryoptcris 

 (L,.). But there are those who insist that homonyms are 

 not permissible, hence they would drop the specific name 

 dryoptcris. The next specific name which could be used 

 is calcarca, — Polypodium calcarcum Pursh+ (non Smith), 

 and accordingly the name would stand Dryoptcris calcarca 

 (Pursh). But calcarca had previously been used by Smith§ 

 for the form now known as Phegopteris dryoptcris robertiana 

 (Hoffm.) Dav. If those, who hold that "once a synonym 

 always a synonym," reached this point therefore they 

 would wholly discard the specific name calcarca, and if 

 they further believed P. robertiana to be distinct from P. 

 dryoptcris the latter would be left without a name ! Or if 



*Flora Boreali-Americana, vol. ii, p. 270. 



fNat. Pflanzenfamilien, 188-189 Lief., p. 175 (1899). 



}F1. Am. Sept., vol. ii, p. 659, (1814). 



§F1. Brit. p. 117 (1804). 



