IOWA PTERIDOPHYTA. 151 



And this suggests other complications. If Lomaria is 

 not recognized as a distinct genus the name Struthiopteris 

 might be applied to the present genus Osmunda, and the 

 latter name might again be retained for the genus 

 Botrychium on the ground that the first species of the 

 genus is the type, and the first species of the Linnean 

 Osmunda are now referred to Botrychium! The foregoing 

 transfers are based on the practices of various botanists, or 

 on views concerning generic relationship and nomenclature 

 actually expressed, and clearly illustrate the causes of the 

 great confusion in nomenclature which actually exists. 



Considering this state of affairs it seems hardly worth 

 while to offer more than a bare list of names, such as will 

 be readily traced or recognized, in a paper of this charac- 

 ter, for it is impossible to make a final disposition of many 

 specific and generic names until the limits of genera are 

 more definitely fixed. 



For that reason some of the names here inserted are 

 used without hesitation because they clearly designate 

 well-defined and well-known species, rather than because 

 the disposition of their nomenclature is considered a 

 finality. Thus on account of the doubt, to which reference 

 has already been made, the generic name Struthiopteris 

 is retained because its use will not add to the confusion 

 already existing, and because the species is thus sufficient- 

 ly marked. That the genus is distinct from Onoclea, 

 however, seems clear. Not only does it differ from that 

 genus in habit of growth and venation, but the indusium 

 approaches that of Cystopteris, while Onoclea resembles 

 Woodsia more nearly in that character. 



Cystopteris is retained because of its long usage, and 

 because it is a question whether Filix Adanson should not 

 be relegated with Lichen and other similar generic names. 



No group of ferns offers greater difficulties to the 



V— 2 5 



