258 CORALS AND CORAL LSLANDS. 



Streams, and much resembles Hawaii in character ; it bears 

 proof in every part of being the last seat of the volcanic fires 

 of the Samoan Group. Its reefs are consequently few and 

 small : there is but a narrow line on part of the northern 

 shores, although on the other islands they are very extensive. 



This absence of corals results obviously from the destruction 

 of the zoophytes by heat, consequent on volcanic action. 

 Submarine eruptions, which are frequent as long as a volcano 

 near the sea is in action, heat the waters and destroy what- 

 ever of life they may contain. After the eruption of Kilauea, 

 in 1840, there were numerous dead fish thrown on the beach; 

 and many such instances in different regions are on record. 



The agencies affecting the growth of coral reefs being before 

 the mind, we may proceed to notice the actual distribution of 

 reefs through the coral seas. The review given is a rapid 

 one, as our present object is simply to explain the absence or 

 presence of reefs within the coral-reef limits by reference to 

 the above facts. 



In the valuable work by Mr. Darwin, the geographical dis- 

 tribution of reefs is treated of at length. The facts here 

 detailed have been obtained from independent sources, except 

 where otherwise acknowledged. In accounting for the cha- 

 racter and distribution of reefs, Mr. Darwin appears to attribute 

 too much weight to a supposed difference in the change of 

 level in different regions, neglecting to allow the requisite 

 limiting influence to volcanic agency, and to the other causes 

 mentioned. His conclusion that the areas of active volcanoes 

 in general are areas of elevation, and not of subsidence, and 

 the inference that reefs are absent from the shores of islands 

 of recent volcanic action on this account do not accord with 

 the facts above stated : for example, the condition of Maui, 

 that it has no reefs on the larger half, that of the volcanic 

 cone of recent action, but has them on the other half whose 

 fires were long since extinct ; for it is not probable that one end 

 has been undergoing elevation and the other subsidence. 



Pacific Ocean. — The west coast of South America is known 

 to be without coral reefs even immediately beneath the 



