78 THE CORAL EEEFS OF THE 



that of the Archipelag^o itself^ and the physical 

 appearance of the other islands leads me to believe 

 that the same rock prevails there also. 



One of the most remarkable featm'es connected 

 with the Louisiade Archipelag"o is the manner in 

 which its shores are protected by the coral reefs 

 which have frequent!}^ been alluded to in the pre- 

 ceding* pages. The principal of these are g*ood 

 examples of that kind disting-uished by the name of 

 barrier reefs. Rossel Reef has already been de- 

 scribed^ and the only other large one of this descrip- 

 tion which we saw more than a portion of, is that 

 partially encircling- South East Island at a variable 

 distance from the land, then passing" to the westward 

 as far as long. 152° 4:0', where it ceases to shew 

 itself above Avater j thence^ however^ the edge of a 

 bank of soundings (represented on the chart by a 

 dotted line) Avhicli is suddenly met with in coming 

 from the deep blue unfathomed water to the south- 

 ward^ can be traced in a continued line to the west- 

 ward as far as the Jomard Isles^ whence it turns 

 round to the northward for ten miles further^ where 

 our examination ended. This last may be con- 

 sidered as a submarine extension of the barrier^ which 

 probably reappears again above water, and passing 

 to the northward of the Calvados Group, reaches as 

 far as the northern entrance to Cornl Haven, enclos- 

 ing nearly all the high islands of the Archipelago. 

 The expanse of water inside when not occupied by 

 land usually exhibits a de})th of from 15 to 80 



