GENERIC TYPES WITH SPECIAL REFERENCE TO GRASSES 253 
The above examples illustrate the method employed in the selec- 
tion of types. It has been intended to consider all the factors in each 
case and to determine if possible what species represented best the 
author's concept, or, in case two or more species are equally available 
for consideration, to select the type in such a way as to cause the least 
confusion in our nomenclature. Aside from Linnaean genera there 
are comparatively few cases where the evidence does not lead to a 
definite species as the type. In these few cases an arbitrary selection 
must be made in such a way as to cause the least confusion in the 
application of names. 
The type of a genus having been fixed it behooves subsequent 
authors, who would divide genera, to retain the original name for that 
part which includes the type species. 
Bureau of Plant Industry, 
Washington, D. C. 
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