GENERIC TYPES WITH SPECIAL REFERENCE TO THE 
GRASSES OF THE UNITED STATES 
A. S. Hitchcock 
Efforts have been made in recent years to stabilize nomenclature 
by proposing rules to govern nomenclatorial changes. An important 
advance in the progress of nomenclatorial reform was made when the 
idea of types was introduced, the idea that a genus should be based upon 
a type species^ and that a species should be based upon a type specimen. 
In the future an element of stability will be introduced if authors of 
generic and specific names will definitely designate the types of the 
groups they publish, something rarely done except within recent 
years. If the idea of types is introduced into our nomenclatorial 
system, and if the application of the idea is made retroactive, it be- 
comes necessary to select types for groups for which no type was 
designated by the author. 
The present paper is concerned with generic types. Rules have 
been proposed by committees and congresses for the selection of type 
species of genera. The intention has been so to frame these rules 
that they may be applied automatically, that all investigators shall 
arrive at the same result in applying them, and that individual judg- 
ment shall be eliminated. However, it has been impossible to foresee 
all contingencies, and experience has shown that no such set of rules 
can be automatically applied with satisfactory results. I doubt if 
rules can be so framed as to eliminate personal judgment, and I 
furthermore deprecate such an attempt. I believe that an effort 
should be made to agree upon principles and that judgment should 
be used by the individual in making application of the principles to 
individual cases. I furthermore believe that the road to uniformity 
lies through agreement rather than through the arbitrary application 
of rules. From whatever standpoint the question of generic types is 
viewed, it is evident that proposed action to obtain uniformity should 
be based upon a knowledge of the facts concerning a fairly large number 
of cases. 
As a basis for a solution of the question the generic names of the 
grasses of the United States have been investigated, the facts bearing 
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