PREFACE, 
The accompanying paper, by Prof. A. S. Hitchcock, Systematic 
Agrostologist of the United States Department of Agriculture, 
entitled ‘‘Types of American grasses: a study of the American 
species of grasses described by Linnwus, Gronovius, Sloane, Swartz, 
and Michaux,” is an important contribution to our knowledge of 
American grasses. 
It is regarded as of fundamental importance in the critical sys- 
tematic investigation of any group of plants that the identity of the 
species described by earlier authors be determined with certainty. 
Often this identification can be made only by examining the type 
specimen, the original description being inconclusive. Under the 
American code of botanical nomenclature, which has been followed 
by the author of this paper, ‘‘the nomenclatorial type of a species or 
subspecies is the specimen to which the deseriber originally applied 
the name in publication.” 
The procedure indicated by the American code, namely, to appeal 
to the type specimen when the original description is insufficient to 
identify the species, has been much misunderstood by European 
botanists. It has been taken to mean, in the case of the Linnean 
herbarium, for example, that a specimen in that herbarium bearing 
the same name as a species described by Linneus in his Species 
Plantarum must be taken as the type of that species regardless of all 
other considerations. In point of fact, the specimen preserved in 
the herbarium of Linnwus is often not the type specimen of the 
species whose name it bears. Linneus sometimes based a species 
on the figure and description of an older author, but by mistake 
placed in his herbarium a specimen belonging to a similar but distinet 
species. Ile sometimes failed to preserve the specimen on which 
one of his species was based, but later preserved some other specimen 
incorrectly referred to the species. To consider such specimens 
types would be quite contrary to the letter and the intent of the 
American code. 
An examination of the methods pursued by Professor Hitchcock 
in locating and identifying the type specimens of American grasses 
@ Printed in Bull. Torr. Club 84: 167-178. 1907. 
IIE 
