inward increase of the capsules bursting forth, by which means it 

 assumes a semi-lunar shape. Influenced by these reasons, accord- 

 ing to the method of founding the genera of ferns upon the invo- 

 lucre, I have come to the conclusion that plants of this nature should 

 be removed from the rest of the Linnaean Polypods, on account of 

 the situation, shape and condition of the involucre. Nor can they 

 be included in Asplenium, on account of the plainly distinct condi- 

 tion of the involucre, although they approach nearer to this genus. 

 Therefore it seems necessary that I should establish a genus of their 

 own, to which I have given the name Athyrium.'" 



Now it will be seen from this description that Roth distinctly 

 differentiates Athyrium from Asplenium. He places only seven 

 species under the genus, of which A, fontanum and A. Halleri, now 

 recognized as forms of one and the same species, are placed first. 

 In this he follows the universal custom of placing at the head of the 

 list the smallest and simplest forms, not because they are the most 

 typical species of the genus, but because they are the smallest. 

 The next five species are all now recognized as varieties of A. filix- 

 foemina, and these are the ones which conform most clearly to his 

 description of the genus. 



In commenting upon this genus, I would say that more or less 

 of the sori upon each frond are generally straight ; some are ham- 

 ate, like a shepherd's staff ; while in other varieties they are bent 

 double and become hippocrepiform or almost round by age. If we 

 ignore the genus Athyrium, it is easy to see how one authority can 

 be justified for \AajCttvgfiKx-foetnina in Asplenium, while another is 

 equally justifiable in calling it an Aspidium. It has seemed to me 

 that the wiser course is to accept Athyrium as a valid genus, fol- 

 lowing the example of Roth and Newman and Moore, the men who 

 have made the closest study of the genus and the most detailed ex- 

 amination of this particular species. 



Another character of the genus which is distinctly laid down in 

 Roth's description of it, is the " laciniate-fimbriate margin" of the 

 involucre. There is a difference of opinion among authors as to 

 the exact value of such a character as this, even when it is constant. 

 That it is not constant, can be certffied to by all who have examined 

 any considerable number of specimens of our American A. filix- 

 foemina. The free edge of the indusium is generally irregular and 

 somewhat lacerated, but it could not properly be called " laciniate- 

 fimbriate." But the case is different with Athyrium cyclosorum. 

 Perhaps no better evidence of the validity of the genus and of 



