THE PBLEW ISLANDS. 237 



sible, I believe I have discovered so many proofs of its inac- 

 curacy, notwithstanding its theoretical possibility, in the struc- 

 tural conditions which I have observed in those reefs, that the 

 task of disproving it will not be a hard one. In order to do 

 this thoroughly, it will be necessary to investigate the structure 

 of the islands and of the reefs enclosing them. 



II. The atoll of Kriangle. — -This is a true atoll of almost 

 oval form, with its lagoon wholly enclosed by the outer reef 

 and the islands upon it ; there is no channel leading into it 

 from the sea. In order to get into i-', the reef must be crossed 

 at high water at the deepest spot, which is to the south ; but 

 even then this lowest spot is so high that it requires some skill 

 to cross it without accident. The lagoon is from three to four 

 fathoms deep, in some places quite five. The bottom, which 

 is perfectly visible through the transparent water, is covered 

 with sand, and on its level surface lie scattered blocks of coral 

 a few feet high ; here and there plants are growing on them. 



The four islands, only one of which is permanently in- 

 habited, lie on the east side and the south-east end ; the most 

 northerly, which, however, does not mark the northernmost 

 point of the group, is alone called Kriangle; the others, count- 

 ing from north to south, are called Nariungas, Nasingis, and 

 Korack ; they are all low, composed of sand, fragments of 

 corals, and large masses of a peculiar stone which consists 

 almost exclusively of the innumerable shells of a recent 

 Foraminifer, the well-known Tinoporus haculatus. This crea- 

 ture is now living in extraordinary quantities on the exterior of 

 the reef, and in smaller numbers within the lagoon. The islands 

 are quite flat ; the difference in level in their inner and outer 

 edges is not more than a foot or two at most. The rocks of 

 Tinoporus, on the inner side of the islands, lie so high that it is 

 only at high tide that the water touches their base, and they 

 slope slightly inwards towards the lagoon. 



The reef which encloses all the islands on the east is but nar- 

 row ; the outer circumference, as indicated by the breakers at low 

 water, is at most at five or six hundred feet from the shore. It 

 is here quite dead, and exhibits very striking details of structure. 

 It consists of large, almost horizontal banks, covered in spots 



