164 Rhodora [Auqdst 



afterward) used Dryopteris Filix-mas as a synonym under Polystichnm, 

 thus giving rise to the later synonym of Dryopteris Filix-mas, Schott, 

 and yet Schott never adopted the genus ! Now if Adanson estab- 

 lished Dryopteris on Filix mas, the proper combination should be 

 Dryopteris Filix-mas, Adanson, and that would serve to render the 

 disagreement which has been pointed out still more conspicuous. 

 But in considering the claims of A r ephrodiitm we have an entirely 

 different state of affairs. We have here a combination properly pub- 

 lished with a reference that makes the species selected typical of the 

 genus, and within two years a reaffirmation of the generic name 

 accompanied by a fuller description that defined the character of the 

 fructification as the one special generic character, and in this sense 

 the genus has been maintained by good authorities from that time to 

 this exactly as I have before stated in my notes. 



The Swartzian genus Aspidium comprised two well marked divi- 

 sions each characterized by the presence of a definite form of the 

 indusium sufficiently constant to constitute an almost absolute line of 

 separation, the exceptions being either accidental, or temporary, and 

 not of sufficient frequency to affect the general result. Both have 

 circular sori but in one the indusium is round with entire margin, the 

 attachment showing exactly in the centre, thus forming the peltate 

 indusium, which exactly corresponds to Adanson's description "eth 

 parasol," and constituting the basis for Aspidium as reduced, J'oly- 

 stichum or Tectaria ; in the other the margin of the indusium is incised 

 with the attachment apparently one-sided, and forming the one special 

 character, the cordate-reniform indusium, upon which Nephrodium 

 rests. 



The question of the venation is really another matter. There 

 being only free-veined species in our New England ferns, with which 

 alone these notes are dealing, it has not seemed to me necessary to 

 do more than to bring out the historic fact that the early species had 

 free veins, in order to show the true characters of the original species. 

 No account, however, was taken of this fact by Richard, and the 

 presence of free veins in the original species may be taken as an 

 accidental coincidence which does not change the original indusial 

 character on which the genus was based. The subsequent expansion 

 of the genus by the addition of species with connivent veins was a 

 perfectly natural one and cannot vitiate its claims to recognition. 

 Neither can any objection, based on the *' melange" which Richard 



