ON ITS EXTERIOR. YOLCANOES. 373 



able men will sufficiently obviate the possibility of any 

 misunderstanding. 



I prefer to avoid the sectional names arbitrarily and 

 variously given upon grounds respecting either the 

 number and size of islands, or the complexion and de- 

 scent of their inhabitants, Polynesie, Micronesie, Mela- 

 nesie, and Malaisie ( 507 ) ; and begin the enumeration of 

 still active volcanoes in the Pacific or South Sea wi^h 

 those which are to the north of the equator ; and will 

 then proceed to consider, in a direction from east to 

 west, the islands lying between the equator and the 

 parallel of 30 S. The many basaltic and trachytic 

 islets with their countless craters, eruptive formerly but 

 at very different periods, must not indeed be regarded 

 as dispersed without any regularity or definite order. ( 508 ) 

 We can recognise in the greater number that their ele- 

 vation has taken place on extended fissures and subma- 

 rine mountain-ranges, following determinate directions 

 in regions and groups belonging to different systems, as 

 we have seen to be the case in the continental mountain- 

 ranges of Central Asia and the Caucasus ; but the rela- 

 tive positions of the very limited number of volcanic 

 apertures which show themselves contemporaneously 

 active at any particular epoch, are probably dependent 

 on very local disturbances affecting the conducting 

 fissures. If we attempt to draw lines through three 

 volcanoes which are all active at the present time and 

 are 2400 and 3000 geographical miles from each other, 

 without any intermediate cases of eruption, (I mean 

 the volcanoes of Mauna Loa, with Kilauea on its eastern 

 declivity, the conical Mount Tanna in 'the New Hebrides, 

 and Assumption in the northern Ladrones,) such lines 



