376 ALEXANDER AGASSIZ 



distance, the wide or narrow cuts which allow in many- 

 cases the freest access of the sea to the interior of their 

 lagoons. 



Pinaki (Whitsunday) is perhaps the most interesting 

 atoll of the group historically. It was discovered by Cap- 

 tain Wallis in 1767 ; it is about one and a half miles in 

 diameter, is nearly circular, and the continuous land 

 rim has but one narrow entrance, too shallow for row- 

 boats even in a smooth sea. The somewhat diagram- 

 matic sketch of this atoll by Beechey has been so fre- 

 quently reproduced in text books, that it has come 

 to be looked upon as the typical atoll. While it is un- 

 doubtedly an interesting phase in the history of atolls, 

 its constant reproduction has given it a celebrity out 

 of all proportion to its importance, and has gone far 

 to disseminate a very erroneous impression of what 

 an atoll is. In reality, Pinaki, instead of being typical, 

 is quite exceptional. 



The larger of the Society Islands are volcanic peaks, 

 surrounded by barrier reefs, which owe their existence 

 to precisely the same process of denudation and erosion 

 that has taken place in the very similar volcanic islands 

 of the Fijis — Kandavu, Mbenga, Nairai, etc. There is 

 one point, however, in which the barrier reefs of the 

 Society Islands and Fiji differ. In the Fijis, the barrier 

 reefs are generally merely reef flats upon which the sea 

 breaks, with an occasional rocky island or negro head; 

 only rarely are sand keys found there. On the more ex- 

 tensive reef flats of the Society Islands, on the contrary, 

 the barrier reefs are well indicated by long lines of nar- 

 row islets formed from the debris of the reef platform, 

 debris piled up exactly as the land rims of the atolls of 

 the Paumotus. The peculiar aspect of these well-wooded 



