28 



cvclosorum as a species could be found than by taking a vomit; 

 frond of A. filix-foemina rubellum just after the laciniae have un- 

 folded in the spring, and a frond of A. . cyclosorum at the same 

 stage of growth. In rubellum the sori are seen as distinctly as 

 when mature, and even at this early period they are beautifully 

 hamate, and the outer edge of the indusium is simply a little rag- 

 ged. That is all, and there is hardly enough of the raggedness 

 even to be noticeable. On the contrary, the sori on the just open- 

 ing fronds of A. cyclosorum strictum are more often hippocrepi- 

 form than hamate, and are sometimes nearly umbilicate, as if they 

 were drawn together with a puckering string on the side attached 

 to the vein ; while the outer edge is thickly fringed with long cilia 

 plainly discernible to the naked eye, and which under a magnifier 

 are seen to be many-jointed. While these facts show the nature of 

 the genus in both cases, they also show that the fringed indusium 

 can hardly be regarded as a generic distinction, but that in the case 

 of A. cyclosorum it forms a very beautiful instance of specific dif- 

 ference. 



If then we allow that Athyrium is a valid genus, the question 

 naturally arises, " What species shall be admitted as belonging to 

 the genus?" I should answer : all species which conform to Roth's 

 description of the genus ; that is, all species endowed with a greater 

 or less number of hamate or hippocrepiform sori and indusia, that 

 being the character upon which Roth relied in distinguishing the 

 genus from Polystichum and Asplenium.. 



Sir William Hooker, in his Species Filicum, threw discredit 

 upon Athyrium by including with it as a sub-section, Robert 

 Brown's genus Allantodia, which was founded on species having 

 a swollen indusium and a straight, sausage-shaped sorus, as the 

 name indicates. He also stated that "those who maintain the 

 genus (Athyrium} are by no means agreed as to the species that 

 should be included in it." That was not a fair statement. If he 

 were going to judge the genus fairly he should have taken it as its 

 author formed it and not as others had made it by introducing char- 

 acters which the author did not use and evidently did not intend 

 should be used in the genus. Hooker himself was one of the worst 

 of these, for in his characterization of Athyrium as a sub-genus of 

 Asplenium, he says: "Sori generally short; involucres lax, con- 

 vex, straight, or often more or less arcuate and even hippocrepi- 

 form, sometimes with the lobes unequal." He then includes A II- 

 antodia as a section of Athyrium, giving as its character, " Invo- 



