yi PREFACE. 
liberty to incorporate them with his own herbarium, unless some 
express arrangement is made to the contrary. For it is unjust that 
he should sacrifice his time to this kind of enquiry, merely to satisfy 
the curiosity of those who are unable to determine Orchidaceous 
plants for themselves. The author will, however, in all cases 
quote in the intended ** Revision" of the order, the numbers attached 
to the specimens sent to him and preserved by him; so that if those, 
who are so obliging as to communicate them, will preserve dupli- 
cates with similar numbers, they will be able, when that work 
appears, to ascertain what their plants have proved to be. 
In the prosecution of his task thus far, the author has received 
from numerous quarters most essential assistance. He is, how- 
ever, still in great want of communications from some parts of the 
world, as will be seen by the following geographical arrangement 
of the evidence upon which his knowledge of species has been 
formed. 
EunoPEAN species have been supplied by many. botanists, espe- 
cially by the late Baron Jacquin, Professors Tineo and Tenore, 
Dr. Hornschuch, and Messrs. Bentham, Talbot, Strangways, &c. 
Those of SIBERIA and NonrHERN Asia were furnished by the 
late lamented Mr. Prescott, whose access to Russian herbaria 
enabled him to procure several species, of which nothing has been 
seen elsewhere. Materials have been also communicated by Dr. 
Fischer, Professors Ledebour and Bunge, and others; but more 
information is still required for the species of the Southern pro- 
vinces of Russia, and of the more easterly provinces of thal 
power in Asia. 
Of Nortn American species there are few which have not been 
carefully examined. "Those of the United States and Canada have 
been given to the author by Mr. Menzies, Drs. Torrey, Asa Gray; 
and Booth, and by Sir W. Hooker; others have been purchased. In 
addition he has examined the valuable collections formed in Cali- 
fornia and North West America, for the Horticultural Society, by 
Douglas, and in Texas and Carolina by Drummond. For Mexican 
species considerable materials have been furnished by the ample 
collections of Karwinski, in the Royal Museum of Munich; of 
Deppe and Schiede, communicated by Professor Schlectendahl; 
of Hartweg, and others; and by the large importations of living 
plants into this country. But a considerable number of species 
described by Llave and Lexarza, have as yet escaped observation, 
and remain for future determination. 
is greatly needed. 
Information concerning them 
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