TAXONOMIC SUMMARY—ILLUSTRATIONS 17 
one region being included in each) is:—Boreales: Total 66; United States 
28; Mexico 48; Central America 2; West Indies 0; South America 0. 
Aequatoriales: Total 211; United States 0; Mexico 29; Central America 
20; West Indies 38; South America 134. 
Of the Boreales 41, or two-thirds, and of the Aequatoriales 87, or two- 
fifths, are now characterized as new. <A very large percentage of the 
forms that have been accorded specific rank by earlier writers are still 
kept up even though they had passed into synonymy. Later studies, 
especially in the field, in the light of the conclusions now reached, may 
be looked to with confidence not only to bring to recognition many spe- 
cies not yet collected, but to make possible the trustworthy subordina- 
tion or merging of some of the forms that are now held for species. As 
my study has proceeded, I have had the satisfaction of finding my own 
opinion in accord with the view of a number of the most experienced 
systematists, that in а monographie assemblage such as is here offered 
no lasting harm ean eome from the most radieal segregation of forms 
possible on morphologie and geographie considerations, while on the other 
hand a blending of widely dissociated forms or of such as differ greatly 
in their extremes though without as yet definable breaks in the series, 
e.g. P. piperoides, leaves the work to be taken up once more from the 
very foundation, and with referenee to all of the original materials that 
may have survived. 
ILLUSTRATIONS 
To any one who has ever wished to compare an Ameriean mistletoe 
with an authentic illustration, it has become evident at once that such 
illustrations seareely exist apart from the superb plates on which Eichler 
figured many of the Brazilian species. It has been my aim to pieture 
the more essential features of every species without alteration of size, by 
aid of the camera, and if possible from type specimens—not only of the 
species as accepted but of forms which have been given names that have 
passed into synonymy. That every species has been figured, and that 
searcely a half-dozen types, even of synonyms, are unpietured, may be 
my exeuse for adding that words are lacking to express adequately my 
gratitude to the many botanists of Europe and North Ameriea who have 
opened their collections to me without restrictions, and in some cases 
have allowed type material to follow me across the Atlantic or have re- 
placed photographs which were unsatisfactory in the first instance. That 
the manuscript now completed for publication pictures for the first time 
237, or nine-tenths, of the recognized forms, shows more clearly my debt 
to these friends than can be stated in any other words. 
The University of Illinois, 
January, 1, 1916. 
