er Jmm 
METHODS OF STUDY 139 
In our lists of specimens under different species, the name of 
the collector is given in parenthesis, except in the case of our own 
collections, which are designated simply by a number enclosed in 
parenthesis. In certain cases where specimens have not been 
seen, records of collections have been noted in quotation marks. 
Exact dates have been given only in the case: of specimens of 
other collectors. All our own collections noted have been made 
since September, 1897, and as there is comparatively little variation 
from year to year, only the month of collection is noted. Types 
of all new species, and duplicates of a large part of the material on 
which this study is based, will be deposited in the Herbarium of 
Columbia University at the New York Botanical Garden. 
Often a better notion of a species is given by an illustration 
than by a very detailed description, but with illustrations so much 
depends on the variations of the plants and the individuality of the 
author, that it is a matter of convenience to have as many draw- 
ings as possible made on one system, by one person. It has, 
therefore, been our attempt to furnish figures of representative 
specimens of all forms of which fresh material has beenseen. All 
our drawings have been made with the use of the camera lucida, 
and at uniform scales of magnification within the limits of a genus. 
For all the Ulothricaceae, Microthamnion, and the Herposteireae, 
a combination of Leitz ocular 3 and objective „|, oil immersion was 
used; for Myxronema, ocular 3 with objective 7 ; for Draparnaldia, 
ocular 1 with objective 7. The drawings thus made were re- 
duced one half in reproduction. 
In nomenclature, the Rochester code has been followed gen- 
erally, though perhaps not with absolute rigidity in the case of one 
or two generic names. 
The matter of generic types has demanded considerable atten- 
tion. It has been our aim in all cases to use the oldest admis- 
sible generic name that can be anchored to a definite type species ; 
that is, the species placed first under the original description of a 
genus has been considered the type, and in accordance with the 
validity of the genus as thus founded, it has been retained or dis- 
carded.* This method has been followed because it is our con- 
* For a more extended discussion of this subject, see Mem. Torrey Club, 6: 250- 
899. 
252. 
