LOUISIADE ARCHIPELAGO DESCRIBED. 73 



fathoms^ with numerous sunken patches of coral, 

 and several reefs which partially dry at low water. 

 The shores of the islands also are g'enerally protected 

 by fring"ing- coral reefs, the larg-est of w^hich is that 

 extending* off the west and south side of Piron Island 

 to a distance of seven or eig"ht miles, with a well 

 defined border towards Coral Haven. 



At the western portion of the Louisiade Archi- 

 pelag-o the reefs seen by us exhibit g-reat irregularity 

 of outline, continuity, and width. Some are linear 

 reefs, others atolls* more or less distinct in cha- 

 racter, and the remainder are usually round or oval. 

 Viewed as a whole they form an interrupted chain, 

 wdth numerous deep water channels, which termi- 

 nates in the West Barrier Reef of the chart, but is 

 connected wdth the coast of New Guinea by a bank 

 of sounding's, with, probably, a well-defined marg-in. 

 Many low, w^ooded islands are scattered along- this 

 line. I know of no disting-uishing* feature presented 

 by the coral reefs of the Louisiade compared with 

 those which I have seen elsewhere. One remark- 

 able occm'rence, however, connected with them, may 

 be mentioned. While passing- in the ship the most 



* " An atoll differs from an encircling barrier reef only in the 

 absence of land within its central expanse ; and a barrier reef 

 differs from a fringing reef in being placed at a much greater 

 distance from the land with reference to the probable inclination 

 of its snb-marine foundation, and in the presence of a deep water 

 lagoon-like space or moat within the reef."— The Structure and 

 Distribution of Coral Reefs, by C. Darwin, p. 14 G. 



