414 PERCY SLADEN TRUST EXPEDITION 



to form the sandy area on which the settlement stands *. This sand piling is compara- 

 tively unimportant at present, but in future times, as the atoll of Cosmoledo will show, it 

 may be the cause of the existence of land on the atoll. 



I have now dealt with the main physical features of Aldabra, and in summary 

 I would emphasise that the atoll is losing on every side in its fight with sea and weather ; 

 the sea coast is being eaten away ; the lagoon is getting larger ; the rain is dis- 

 solving away the surface of the land and, to balance all, there is only a slight piling 

 of sand. 



V. ALDABRA. THE LAND FLORA AND FAUNA. 



In this section it is intended to give a short account of the land flora and fauna 

 of Aldabra, dealing rather with those groups which will not be the subjects of subsequent 

 reports. 



Flora. A collection was made containing specimens of the majority of the plants 

 of the atoll, though a few trees were never found in flower and so perhaps cannot be 

 identified. The flowering plants will be reported on at Kew, while a small collection of 

 algse are in the hands of Mr. and Mrs. Gepp. 



A certain number of plants were such as could easily be recognised, but the majority, 

 and perhaps the most interesting, were entirely unfamiliar. It is impossible therefore to 

 do more than broadly indicate the cacology of the atoll flora, leaving a complete list to 

 the Kew report. The floral seasons naturally coincide with the climatic, which were 

 indicated in the Introduction. The season of south-east trades is generally a season of 

 drought and rest and, many of the trees being leafless, all forms of bush have then an 

 extremely barren and dead appearance. 



At the end of October signs of renewed life are visible, and after the first rains in 

 November many plants begin to flower often before their leaves have appeared. In 

 December and January the remainder of the plants are in flower, with the exception of 

 a few, which by their condition suggest that they flowered quite at the end of the calm 

 season (March). 



There are roughly four types of vegetation corresponding to four different classes of 

 situation. These are : 



1. Mangrove Swamp. 



2. Pemphis Bush. 



3. Varied or Open Bush. 



4. Shore Zone. 



1. The mangrove swamp fringes the lagoon, but is also found on the seaward coast 

 of the atoll at Camp Frigate and on Magnan Island (in the western channels), where it is 

 protected from the direct force of the waves. It is composed mainly of true mangroves 

 (Rhizophoracese), the genera observed being Rhizophora, Bruguiera, and Ceriops. The 



* See Geographical Journal, September 1910. 



