356 TEAICSACTIONS AXD PEOCEEDIXGS OF THE [Sess. lix. 



Of the 38 native species, Sesuvium PoHidacastrum is 

 the only one which grows in all the six islands of the 

 group; and in the two small rocky islets of He aux Tons and 

 Eocher des Oiseaux this species is the only one which occurs. 



The native flora of this group of islands is of a tropical 

 maritime character. The number of species is small. The 

 rocky coralline limestone, the absence of fresh water, and 

 the frequent saturation of the ground with saline spray, 

 are all conditions unfavourable to the growth of a large 

 number of species. The number of species to a natural 

 order is only 2 on an average; and the 38 native species 

 belong to 35 different genera. Portvlaca, Ijpomcea, and 

 Ramcdina contain 2 species each, and the remaining 32 

 genera only 1 species each. There is an entire absence of 

 trees, and the tallest shrub does not exceed 6 feet in height. 

 All the plants of Bocrhaavia diffusa, gro^ving on the 

 coralline limestone have a pale green perianth-limb, with 

 white lobes and white filaments, whereas all the plants of 

 the same species, observ^ed by me, gi-owing on the volcanic 

 tuff in Eound Island in 1889, had a purple perianth and 

 dark purple filaments. 



There are 8 naturalised species, which all belong to the 

 Dicotyledons. They occur in the two inhabited islands of 

 He aux Fouquets and He Marianne, and in He de la Passe, 

 which was formerly occupied by troops. Sophora tonLcntosa 

 in He IMarianne, Ojyuntia monacantha and Ipomcea Nil, in 

 He de la Passe, and Xicotiaim Tabacum in He aux Pouquets, 

 are not recorded as naturalised in Mauritius by Baker. 



There are 7 planted species, which all belong to the 

 Dicotyledons. They occur in the two inhabited islands 

 of He aux Fouquets and He Marianne, near the lighthouse 

 and caretaker's house respectively. 



The remainder of my paper contains a complete hst of 

 all the plants observed by me in each of the six islands of 

 the group. I have followed the nomenclature of Baker's 

 " Flora of Mauritius and the Seychelles," so far as the 

 species are described in that book. The Cryptogams were 

 identified by Mr. G. ^lassee and Mr. C. H. Wright, of Kew 

 Herbarium, and I am also indebted to Mr. X. E. Brown 

 and Dr. 0. Stapf, of the same institution, and to Mr. C. B. 

 Clarke, for the identification of some critical species. 



