﻿THE FERN BULLETIN 



77 



does not grow in the same situations ; in fact, the or- 

 dinary Cystopteris fragilis does not appear to occur at 

 all in this region. Since recent rules of nomenclature 

 make special inducements for changing the names of 

 plants when the plant is changed from variety to spe- 

 cies, it may be observed that this plant may also be 

 called Cystopteris tenuifolia, and Filix fragilis tenui- 

 folia.—W. N. C. 



A QUESTION OF NOMENCLATURE. 



BY A. A. EATON. 



The editor of the Bulletin seems to enjoy the unique 

 position of being the only person who at present ad- 

 heres to the principle that a name given to a variety 

 must be retained if the variety becomes a species, and 

 inversely a name given to a species must be retained if 

 the species is reduced to a variety. Article 49 of the 

 Vienna Code reads in part: "When a subdivision 

 ( variety) of a species becomes a species, or the reverse ; 

 and generally speaking, when a group changes its 

 rank, the earliest name received in its new position 

 must be regarded as valid." It is recommended, how- 

 ever, that the old name be carried over. This is one 

 of the few points in which the Vienna and American 

 codes agree. Indeed, Dr. Underwood in conversation 

 with me singled it out as the only rule of the Vienna 

 Code that was worthy of adoption. Let us illustrate 

 this rule by instances in recent numbers of the Fern 

 Bulletin. Several years ago I described Isoetes Dodgci. 

 Later, when I had access to Dr. Engelmann's material, 

 I found it to be his /. riparia var. Canadensis. Doubt- 

 less the only reason Dr. Engelmann made this a var- 

 iety was because his material was rather under-ripe and 



