VI PREFACE. 
The third part embodies the results of an. investigation by Prof. 
A. S. Hitehcock, Systematic Agrostologist of the United States 
Department of Agriculture, under the title, “Types of American 
grasses: a study of the American species of grasses described by Lin- 
neus, Gronovius, Sloane, Swartz, and Michaux.” 
This paper is an important contribution to our knowledge of Ameri- 
can grasses, from the nomenclatorial point of view. It is regarded as 
practically a necessity in the critical systematic 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 descrip- 
tion 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 describer 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 HKuropean 
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 Linneus is often not the type specimen of the 
species whose name it bears. Linnwus 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. He 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 
in European herbaria is earnestly commended to those botanists 
who are not familiar with the method of types or who are opposed 
to its application. 
Opportunity was kindly given by various curators for the exami- 
nation of specimens. Acknowledgment is made, however, to 
B. Daydon Jackson, Carl A. M. Lindman, P. I. Lecomte, and A.B. 
Rendle for special courtesies and assistance rendered by them in 
facilitating the examination of colle Te tions in their charge. 
a Printed i in Bull. Torr. ¢ Club 34: 167-17 1907. 
