VAVAU. 197 



connect them ; south of Uiha the reef flats extend as a narrow belt towards 

 Tofanga Island, and to the south of Ava Mata Mata Vika (PI. 218) the 

 reef flat is merely a narrow line reaching to the southern horn of the bank, 

 on which there is only a single snaall island, Lima. Remnants of the ele- 

 vated limestone crop out as outliers on the naiTOw reef fringe, some of them 

 attaining, according to the charts, a height of a few feet. 



On account of the weather we did not venture into the labyrinth of 

 patches to the west of Lifuka, and were imable to examine the peculiar 

 atolls sketched on the chart of the northern part of the Haapai group.^ 

 They differ from the greater number of the islands of Haapai and Nomuka, 

 which are surrounded by extensive fringing reef flats, in having an outer 

 somewhat raised edge forming an incipient barrier reef, resembling the 

 raised barrier edge of the fringing reef of the larger islands like Foa, Haano, 

 Lifuka, Uoleva. The transition of an island with its fringing reef to one 

 of these incipient atolls is shown by comparing such islands as Luangahu 

 (Pis. 217, 218)," an islet with an extensive fringing reef, with. Lofanga, 

 an elevated coralliferous limestone island (150 feet), or Moungaone (100 

 feet in height), which has in part a fringing reef, in part a barrier reef, to 

 such an atoll as Xiniva, or Ofolanga, or Hakau Lahi, the remnants only 

 of islets encircled by a narrow barrier reef enclosing a space full of dry 

 coral patches. The earlier stages, Lofanga, Moungaone, Tongua, Kotu, 

 Haafeva, patches or outliers of the great Haapai land (Pis. 217, 218), 

 resemble the condition of the large eastern islands of Uiha, Uoleva, 

 Lifuka, and Haano, which in their turn recall the existing condition of 

 the northern parts of Tongatiibu. 



Vavau. 



Plates 120-125, 219. 



Approaching A'avau from the southwest, we come upon the triangularly 

 shaped island, Hunga, forming- the western entrance to the Vavau group 

 (Pis. 121, fig. 1 ; 219). To the east two immense white patches appear on 



' A. Cliait 30yy. 2 ii,ij _ 3099 and 3100. 



