OF THE MALDIVE ISLANDS. 
147 
Consider first the wind. South of latitude 10° S. the 
south-east trade blows throughout the year. North of this 
is the monsoon region, in which from April to September 
there blows the south-west monsoon of India and Ceylon, 
and from October to March the north-east monsoon. South 
of the equator the wind is south-east, at the equator about 
south, and north of the equator it is south-west to west. 
In the other monsoon the wind is north-east over Ceylon, 
northerly nearer to the equator, and north-west to the 
south of it. 
Now consider the currents. The great equatorial current 
fiows all the year round in a westerly direction, passing 
through the Malay Archipelago (especially between Java 
and New Guinea and Australia), and crossing the Indian 
Ocean south of the equator. It splits south of the Chagos 
Archipelago, the northern half going round the Seychelles 
and returning along the equator to Sumatra. Part of the 
southern stream reaches and rejoins this via the Mascarene 
Islands and Madagascar. North of this constant stream in 
the trade-wind region are the variable currents of the 
northern Indian Ocean, which change with the monsoons. 
In the south-west monsoon the currents run in general to 
the east, in the north-east monsoon to the west, round the 
Arabian Sea and the Gulf of Bengal, as shown on .the 
maps. 
Now consider the probable results to be expected in a 
long period of time during which these causes work together. 
The equatorial westerly current, aided by the south-east 
trade-wind, will carry to the Seychelles all or nearly all 
those littoral species of the southern parts of the Malay Archi- 
pelago and North Australia which have adaptations good 
enough to carry them safely over the long distance. On the 
way a few species may be left in the Chagos Archipelago, 
but these islands do not lie in the main course of the 
current, nor offer any great intercepting area. The return 
current will carry the littoral fiora of the Seychelles to some 
( 20 ) 
