150 



this paper. The species of flowering plants represent 127 genera 

 and 54 families. 



Similar proportions are characteristic of insular floras of both 

 smaller and larger dimensions. Taking Benthani and Hooker's 

 classification in a somewhat modified or extended sense, these 

 54 families constitute about one-fourth of the generally recog- 

 nised families of the phanerogamic or flowering plants of the 

 world. Over one-third (19) of these families are represented by 

 only one species each, and, it follows, by only one genus each. 

 15 families are represented by only 2 species each, and 5 by 

 3 species, whilst 6 others number 4 species each. These 5 

 families account for 88 species or considerably more than half 

 of the total number. For the rest, the Gramineae number 14 

 species; the Rubiaceae 15, and the Leguminosae 12. The 

 average of species to a genus is rather less than 1"4 in the whole 

 flora . 



Noteworthy among the genera represented by only one species 

 in Aldabra are Erythroxylon, Ochna, Macpliersonia, Side- 

 roxylon, Jasminum, Salicornia y Vis cum, Arigraecum, Dion- 

 corea, Lomatophyllwm, Pandanus and Acrostichum. Most of 

 the genera named have a wide geographical area; but Macpher- ) 



sonia and Lo matopliyllum are regional. There is only one genus 

 of phanerogamia confined to the small islands under considera- 

 tion, namely, Apterantha in Aldabra. The small number of 

 Compositae (four) and the absence of Labiatae are remarkable ; 

 and the large and almost universally spread Scrophulariaceae 

 are present only in the cosmopolitan Hevpestis Monnieria. 



The presence of Lorantlins and Viscum in Aldabra, as well as 

 of the Orchids, Acampe and Angraecum, is specially interesting 

 because these elements are apparently wanting in all the other 

 islands, except Agalega, of the Seychelles area, outside of the 

 Seychelles Archipelago proper; Disi'eris tripetaloides 3 a terres- 

 trial orchid, is recorded by Baker from Agalega. Disperis is 

 mainly South African with a few Mascarene and Indian species. 

 Orchids, it may be mentioned in passing, are exceedingly rare 

 in remote islands of small and moderate dimensions, or entirely 

 absent. Thus there is none in the islands of the South Indian 

 Ocean from St. Paul and Amsterdam and Kergulen to the 

 Crozets and Heard Is] and. There is none in the south Atlantic 

 Islands from Ascension to Tristan da Cunha and South Georgia, 

 save four species in the Falkland*. Turning to the North 



Pacific, the Sandwich Islands possess only 3 species of 



Orchids; Guada loupe Island, off the coast of Lower California, 

 none; Galapagos, 2 or 3; Juan Fernandez, none. On the other 

 hand, the islands to the south of New Zealand include orchids 



in decreasing numbers southward; the Auckland group sheltering 



about a dozen species; the Campbell half-a-dozen, and the 

 southernmost Maoqnarie IsLmd none at all. Absence from the 

 last-named island is not due to unfavourable climatic conditions. 

 About a dozen species of Orchids inhabit Seychelles and they 

 are numerous in the Mascarenes. On the other hand, the dis- 

 tant Laccadives, Maldives and the Chagos Archipelago are also 

 destitute of this family. 



The large, almost cosmopolitan family of Rubiaceae consti- 



