18'::^: 



PREFACE. 



descends belo-w the freezing point, but the island is exposed to frequent 

 and violent winds. 



The numbers in the following Table are taken, for Aden, from Dr. T. 

 Anderson's ' Florula Adenensis ' (Journ. Linn. Soc. Lond. vol. v. SuppL), 

 a work drawn up on the same standard as to the limits of genera and 

 species as the Hongkong Flora ; and for Ischia, from Prof Gussone's 

 ' Enumeratio Plantarum Yascularium in Insula Inarime provenientium ' 

 (Neapoli, 1854). From the latter however I have found it necessary, 

 in order to establish a fair comparison, to deduct the cultivated species, 

 and to reduce the remainder to the specific and generic standard of our 

 Hongkong Flora. 



* The discrepancies between the total number of Orders and genera in this and the pre- 

 ceding Tables is owdng to the half-naturalized species being here reckoned, but necessarily- 

 excluded when considering geographical areas. 



