18 
INTRODUCTION. 
In this catalogue the descriptions of the different species given 
in the text are taken from specimens I have personally examined ; 
a list is appended at the end of each genus of such as are not repre- 
sented in the collections to which I have had access, and in these 
cases the definitions are copied from the books in which they are 
described. I am far from supposing that my work is free from 
inaccuracy, bub every species of which I have given the characters 
can be examined, either in bulk or as a mounted object, in the 
British Museum collection. The specimens I have supplied to 
supplement the collection are indicated in the following pages 
under .each species by the letters L:B.M. 
The rules which govern the nomenclature of species, laid down 
by Alph. de Candolle, " Laws of Botanical Nomenclature" (1868), 
and adopted by botanists, require that the first authentic specific 
name published under the genus in which the species now stands 
shall take precedence of all others. Compliance with this direction 
has occasioned considerable alteration of the names given in 
Eostafinski's Monograph, in which work a severe attention to 
this important principle has not been observed. I am greatly 
indebted to Mr. Oarruthers, who, in addition to other valuable 
assistance, has traced the history of each species in the volumes 
of the British Museum Library, and made the necessary corrections. 
1 offer my grateful acknowledgments to those through whose 
courtesy I have been enabled to study the various herbarium 
specimens that have come under my notice ; to the Director of 
the Boyal Gardens at Kew for giving me special facilities for 
investigating the collection under his care, which includes 
Berkeley's precious series, containing a great nixmber of original 
types from India, New Zealand, and America that supplied 
Rostafinski with a large part of the material introduced into 
the Appendix to his Monograph. These types are to a large 
extent duplicated in Broome's and Eavenel's collections in the 
British Museum. To Professor Bayley Balfour I return my 
thanks for much friendly assistance and for. the opportunity of 
inspecting the specimens in the Royal Herbarium at Edinburgh, 
including Greville's collection and an almost complete set of 
type examples supplied by the late Professor de Bary ; to Professor 
van Tieghem for the inspection of the collection of the Paris 
Museum ; to Professor A. Blytt for an opportunity of examining 
the most important types in the Museum at Christiania; to 
Dr. Boerlage for giving me access to the Leyden collections ; and 
especially to Graf zu Solms-Laubach for the privilege affoi'ded me 
of inspecting de Bary's invaluable collection at Strassburg, con- 
taining a large proportion of the type specimens referred to by 
Bostafinski in his original Monograph ; to Dr. Rex, of Phila- 
delphia, for a neai'ly complete series of the species found in the 
United States of America, now represented in the British Museum 
collection, and for the communication of his views on a group to 
which he has devoted many years of careful research. I am also 
grateful to my friend Professor Farlow for many valuable speci- 
