PRELIMINARY REVISION OF THE NORTH AMERICAN SPECTES 
OF ECHINOCACTUS, CEREUS, AND OPUNTIA, 
PREPATORY NOTE. 
This is the completion of the work on our North American Cactacez, 
which was begun by the preliminary revision of Cactus, Anhalonium, 
and Lophophora, published as Contributions from the U.S. National 
Herbarium, Vol. HII, No. 2 (issued June 10, 1894), The occasion for 
such an undertaking and the opportunities for carrying it out were 
explained in the prefatory note to that paper. As the work pro- 
gressed, however, it became more and more evident that the revision 
could consist only of the systematic collection of our present knowl- 
edge, based upon the study of the very inadequate material accessible 
in herbaria and gardens. The difficulties of the group, as regards types 
and nomenclature, were pointed out in the previous paper, and the 
undertaking would have been abandoned only that it seemed but 
proper to contribute to the knowledge of the group such facts as had 
come to light in the course of several years’ study, especially as an 
excellent opportunity had been given to examine Dr. Engelinann’s 
types and unpublished notes. It may be well to repeat the statement 
here that all known forms within the United States have been included, 
but only such Mexican and West Indian forms as could be personally 
examined. A maze of names and descriptions have been handed down 
in various writings, but it would be of no advantage to introduce them 
except as substantiated by specimens. 
JOHN M. COULTER. 
UNIVERSITY OF CHICAGO. 
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