8 
allowed; acknowledgments of assistance in this part of the work 
are due Capt. John Donnell Smith, of Baltimore, Md., and Dr. B. 
L. Robinson, of Cambridge, Mass. This process of verification 
has taken a great deal of time and has disclosed a very remarkable 
number of inaccuracies in ordinarily accepted citations. The at- 
tempt has so far succeeded that somewhat more than 98 per cent. 
of the citations given are known to be exact, and a careful list 
of the unverified citations has been kept for future reference. 
It will doubtless be found that in a very few instances the 
committee has not carried out the instructions under which it was 
acting, but in a work of such magnitude an occasional error could 
hardly be prevented. Inasmuch as in the further exploration of the 
area additional species and varieties are certain to be brought to 
light, and the inevitable change in view from time to time relative 
to the rank of various forms as species or varieties and of the limi- 
tations of genera, will from time to time make other editions of 
the list a necessity, opportunity will be afforded for the correction 
of any errors which may have crept into the present work. 
As to the publication of the list, it was at first thought that the 
committee might issue it as a pamphlet and assume the necessary 
financial responsibility, but, this method being found impracticable, . 
a proposition from the editor of the Torrey Botanical Club to 
publish it in the Memoirs of that organization was accepted. It 
has been issued in signatures to members of the committee and 
such other botanists as have expressed a desire for it, each signa- 
ture being dated with the day of delivery to the editor and dis- 
tributed immediately thereafter. 
There has been brought together in an appendix to the list 
the names of additional species and varieties found in the area 
during the past season, which have been brought to the attention 
of the committee, together with others inadvertently omitted in 
the compilation and some corrections of citation. The committee 
deems it desirable that appendices be published annually, so that 
the record of plants occurring within the area may be kept up to 
date, and that modifications of unverified citations may be indi- 
cated when necessary. 
