VI PREFACE. 



The Volume is completed by an Index containing nearly 

 1700 names. 



In conclusion, the author begs to acknowledge with 

 thanks the valuable assistance afforded by his foreign cor- 

 respondents, particularly those in Germany, France, and 

 Mexico. He desires also to express his obligations to 

 Mr. R. Pince, of the Great Exeter Nursery, and Mr. H. 

 Low, of the Clapton Nursery. 



G. G. 



London, May ^Ist, 1858. 



