220 APPENDIX. 



appear to be fronted by distant reefs rising abruptly from the 

 sea, and within some of which, there is reason to believe that 

 the water is deep. I have therefore little doubt that they 

 belong to the barrier class. In the southern part of the group, 

 we have Elisabeth Island, which is surrounded by a reef at the 

 distance of a mile ; and two miles eastward of it (Krusenstern, 

 Append. 1835, p. 42) there is a little island containing a 

 lagoon. Near here, also, lies Circular Eeef (Horsburgh 

 Direct, vol. i. p. 691, 4th edit.), ' three or four miles in dia- 

 meter, having deep water inside with an opening at the 

 N.N.W. part, and on the outside steep to.' I have from these 

 data, coloured the group pale blue, and Circular Eeef dark 

 blue. — The Anachorites, JEchequier, and Hermites consist of 

 innumerable low islands of coral formation, which probably 

 are atolls ; but not being able to ascertain this, I have not 

 coloured them, nor Durour Island, which is described by Car- 

 teret as low. 



The Caroline Archipelago is now well known, chiefly 

 from the hydrographical labours of Lutke : it contains about 

 forty groups of atolls, and three encircled islands, two of which 

 are engraved in Figs. 2 and 7, Plate I. Commencing with the 

 eastern part, the encircling reef round Ualan appears to be 

 only about half a mile from the shore ; but as the land is low, 

 and covered with mangroves (Voyage autour du Monde, par 

 F. Lutke, vol. i. p. 339), its margin has not probably been 

 ascertained. The extreme depth in one of the harbours within 

 the reef is 33 fathoms (see charts in Atlas of Coquille's 

 Voyage), and outside at half a mile distance from the reef, 

 no bottom was obtained with 250 fathoms. The reef is sur- 

 mounted by many islets, and the lagoon-like channel within 

 is mostly shallow, and appears to have been much encroached 

 on by the low land surrounding the central mountains ; these 

 facts show that time has allowed much detritus to accumulate ; 

 coloured pale blue. — Pouynipete or Seniavine. In the greater 

 part of the circumference of this island, the reef is about one 



