Preface. xiii 



quency of trade with the places mentioned, and the 

 opportunities there were of disseminating this useful 

 tree. The remarks of Renaud are especially interest- 

 ing, as they show that trade between Western Asia, 

 India, the Malay Archipelago, and China, dates from 

 the time of the Phoenicians, Greeks, and Romans. 



There ought properly to have been added a chapter 

 on the insects which are inimical to the citrus tree. 

 Some of these may, however, be of use to it, although 

 they feed on its leaves. Researches in Entomology, 

 however important, would have made this volume 

 interminable, and might have possibly put off its pub- 

 lication for ever.* 



Wherever there is a want of fulness of description 

 in the text, it may be found supplemented on the back 

 of the plates of the Atlas. 



In some plates I have not been able to give draw- 

 ings of typical leaves. It is difficult in corresponding 

 with persons in various parts of India to impress them 

 with the necessity of sending typical leaves. I have, 

 therefore, been often obliged to give only the outlines 

 of those that came with the specimens. These leaves, 

 however, have often, I think, a morphological interest 

 of their own. By typical leaves I mean the fully 

 developed ones of the adult tree or adult branch, and 

 such as give the character to the tree. This defect 

 in some of the plates will, however, be found gene- 

 rally supplemented by typical leaves of the same 

 variety in other plates. 



I have always thought that a good Index to a book 

 is one of its most useful parts ; and so I have endea- 

 voured to make one as full as I could. Through the 



* Recently an illustrated work has been published by the Italian 

 Government, entitled " Studi sugli Agrumi," and the author is said 

 to be Penzig. 



