IOWA PTERIDOPHYTA. 153 



and until generic limits are better defined; and the writer 

 prefers to retain the well-known Nephrodium for the 

 present because its use cannot in the least increase the exist- 

 ing confusion, and may be a final necessity. Phegopteris 

 is retained in its original sense for the clearly non-indusiate 

 forms . 



It is easy to subscribe to Diels',and Underwood's 

 restoration of the genus Ptcridium for our Pteris aquilina 

 L,., the double involucre separating it at once from Pteris. 

 Equally satisfactory is the transfer of Pellcsa gracilis Hk. 

 to the genus Cryptogramma under the earliest specific 

 name stelleri, provided the genus Cryptogramma is to be 

 maintained, which seems desirable. 



The genus Adiantum is removed from the Pteridiecs and 

 placed in a separate family, — John Smith's Adiantece . 

 The position of the sori on the reflexed involucre, and the 

 habit and texture of these ferns certainly entitle them to 

 take rank as a family with such groups as Davallica; and 

 Lindsay ecz . 



Still other changes may be necessary. Thus, as already 

 stated, the eusporangiate ferns, — the Ophioglossacece and 

 Marattiacecz , the latter of course not represented in Iowa, 

 may have to be removed from the class Filices (and from 

 each other) , and the Sclaginellacecz and Lycopodiacecc may 

 also take rank as related classes. However, further com- 

 prehensive comparative study is necessary before these 

 points can be satisfactorily decided. 



The following is a complete list of the Iowa Pteridophytes 

 in the State University Herbarium in April, 1901. Unless 

 the collector's name is given the specimens were collected 

 by the writer. 



