VI PKEPACE. 



as the materials wliicli came to hand enabled us to complete 

 each, as far as practicable, without reference to their 

 systematic order of sequence. This has necessarily deranged 

 the paging of the whole work, 1)ut with the aid of the 

 systematic and alphabetical indexes to the genera appended 

 to each volume, little inconvenience will, it is hoped, be 

 experienced in finding any of the described species. 



Little explanation of the plan of the work is here needed ; 

 we have only to state that in the scientific classification 

 and sequence of the genera we have followed, with but 

 trifiing deviations, the arrangement of Bentham and Hooker 

 as elaborated in their Genera Plantartwi, the most profound 

 and, at the same time, the most intelligiljle exposition of 

 the Orcliide£e extant. In the nomenclature of the species 

 we have adhered to the Laws of Botanical Nomenclature 

 adopted by the International Botanical (Congress, held at Paris 

 in August, 1867. 



Li the description of the species, we have been compelled 

 to use occasionally a few technical terms ; at the end of 

 the second volume we have given a glossary of the terms 

 so used. In the cultural notes we have quoted temperatures 

 in the (-entigrade scale with the equivalent Fahrenheit 

 readings, in the hope that the far more rational scale, now 

 almost universally adopted in scientific investigations, may 

 also come into use in horticulture. The literary references 

 in italics indicate coloured plates of the species or variety 

 described. 



We gratefully acknowledge our deep obligations to the 

 numerous patrons and friends who have with untiring 

 kindness supplied us with materials for description and 

 illustration of rare and little known kinds, without wdiich 

 the issue of this work in its present form would have been 

 impossible. The various sources from which these materials 



