HITCHCOCK AND CHASE—NORTH AMERICAN PANICUM. 9 
States or countries, the States being in the sequence followed by 
the Century Atlas, the other countries and provinces being inter-. 
polated or added with the intention of preserving the general sequence 
from north to south. Mexico and Central America precede the West 
Indies. The islands of Tobago and Trinidad are considered as 
belonging geographically to South America and are listed after 
Venezuela. All specimens cited in the distribution or mentioned in 
the notes are in the United States National Herbarium unless other- 
wise stated. Specimens from other herbaria are cited from States or 
countries when such specimens add to the known range or fill in gaps 
in the listed distribution. In such cases only one specimen is men- 
tioned from each additional State, unless the species is rare or of 
peculiar distribution. These additions are taken from other herbaria 
in the following order: Hitchcock’s herbarium, Gray Herbarium, 
herbarium of the Academy of Philadelphia, herbarium of the Mis- 
sourl Botanical Garden, Biltmore Herbarium, herbarium of the Field 
Museum, the herbarium of the New England Botanical Club, and 
other local herbaria in no particular sequence. 
In order to save space, specimens are cited by collector and number 
only, or, if the collector’s number is not given, the year is stated.? 
This method makes clear in most cases the identity of the specimens 
listed. It must be borne in mind that when a specimen is cited by 
the collector’s number it refers to the particular sheet in the National 
Herbarium or other herbarium mentioned. It not infrequently 
occurs that two or more species, collected at the same time and place, 
or collected at different times and places but supposed by the collec- 
tor to be the same species, are distributed under the same number to 
different herbaria. Collectors have in some cases sent to the National 
Herbarium a set of grasses for identification, and later distributed 
other sets in which the species under certain numbers were different 
from those submitted for names. This is especially misleading if the 
labels state that the sets have been determined at the National 
Herbarium or the Department of Agriculture or by a specialist whose 
name appears upon the label. The numbered sets collected by 
Charles Wright in Cuba, which contain many examples of more than 
one species distributed under one number, have been discussed in an 
earlier publication. ® 
The locality cited in the distribution does not always exactly agree 
with that given on the label. Occasionally, for convenience, several 
specimens from the same general locality are listed under one head- 
ing; for instance, ‘‘ Vicinity of Cape Henry” may include specimens 
labeled “Virginia Beach” or ‘‘Lynn Haven.” This has not often 
@ Smith 1900 indicates that the specimen is Smith’s number 1900; Smith in 1900 
indicates that the specimen was collected by Smith in the year 1900. 
b Hitchcock, Contr. Nat. Herb. 12: 185. 1909. 
