18 



PREFACE. 



descends below 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 Vascularium 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 Orders most numerous in species 



Gramineae 

 Filices . . . 

 LeguminossB . 

 Composite 

 Cyperacea3 

 Euphorbiaceas 

 Rubiaceae . . 

 Orchideae . . 

 UrticesB . . 

 Scrophularineae 

 Acanthaceae . 

 Verbenaceae . 

 Labiatae . . 



86 species. 



75 



72 



67 



62 



52 



42 



36 



27 



21 



18 



17 



16 



6 Orders have 8 species each. 



5 „ 7 „ 

 11 „ 6 



6 „ 5 „ 



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

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

 excluded when considering geographical areas. 



