46 JOURNAL OF THE ARNOLD ARBORETUM [vol. i 



name, wliile under difTerent generic limitations the name liad to be changed 

 to P. pidchcrrima, if no distinction is made between laxonomic and nomen- 

 clatorial synonyms. As an exam])le concerning specific names within the 

 same genus, Rosa vjicrophylla Roxburgh (18^20), may be quoted; this name 

 cannot be maintained, as there is an older R. inicrophylla Desfontaint^s 

 (1798) which, though generally referred as a synonym to R. scmpervirens 

 L., does not represent the type of that s])ecies and therefore maybe revived 

 by an author favoring narrower specific limits. On the other hand, a name 

 like Qucrcus lanuginosa Thuillier (1799) is to be considered valid, though 

 there is an older Q. lanuginosa Lamarck (1778) which, however, is not 

 valid, as it is a nomenclatorial synonym of Q. Cerris L. (1753) being based 



on that species. 



One of the most difficult ])roblems is the nomenclature of varieties and 



other subdivisions of species. Many botanists consider the different grades 

 of subdivision of species as su})ject to the rules governing the change of 

 rank, while others preserve even the original author citation when changing 

 a variety to a form or vice versa. One of the chief objections against the 

 former practice is the lack of restriction i)laccd on the number of subdivi- 

 sions, for according to art. 12 one is allowed to intercalate as many sui)])le- 

 menlary groups as one sees fit, and the absence in many cases of the exact 

 designation of the nature of the different grades, which often are preceded 

 only by letters, numerals or typographical signs, or are joined directly to 

 the specific name (so-called trinomials). Even if such terms as variety or 

 form are used, they are frecpiently employed in a vague sense and may have 

 different value in different publications. It is difficult to see how we can 

 api)ly to subdivisions whose grade is not clearly defined the strict rules 

 governing change of rank without introducing many unnecessary changes 

 on account of difi'ercTit opinions on the valuation of certain names. The 

 possibility also is thereby given to change at will almost any name of a 

 subdivision by changing the designation of the grade, e. g. by calling a form 

 a lusus, a subvariety a form, a variety a subspecies; though suc^h changes 

 are against the recommendations, they are not against the rules, and once 

 made, whether intentionally or inadvertently, they cannot be revoked. 



To make the nomenclature of varieties as stable and simple as possible, 

 it seems best to consider as groups of different rank only those restricted to 

 definite numbers, that is the main groups as enumerated in article 10 and 

 their subdivisions as given in article 11, counting the subdivisions of each 

 main group as one unit, that is as one rank, while the different kinds of sub- 

 divisions as admitted by art. 12 which are of an indefinite number, may 

 be considered grades or degrees of subdivision. Regarding the question 

 whether the different subdivisions of species should ])e considered ranks, it 

 seems significant that among the numerous examples illustrating change of 

 rank, none is given which illustrates the change of any grade of subdivision 

 to another grade of subdivision of the same species. It also is to be noted 

 that apparently subdivisions of a genus, as subgenus and section, are not 



considered as constituting different ranks, as shown by the first example 



