AGASSIZ: FIJI ISLANDS AND CORAL REEFS. 63 



that the honeycombed pitted pinnacles of hard ringing limestone should 

 be mistaken by inexperienced observers for volcanic clinker-like rocks, 

 and the locality described as volcanic, especially when taken in connec- 

 tion with the crater-like aspect of the sounds. The island is surrounded 

 by a fringing reef nearly a mile in width in some places, and with a pas- 

 sao-e forming a shallow and very narrow lagoon with a depth of four to 

 hve fathoms between the outer reef flat and the shore line along parts of 

 the eastern and of the western face of the island. There is a narrow 

 passao-e (Plate 82) on the northeastern face into tlie interior basin, but 

 too shallow to have admitted the " Yaralla." In addition there are also 

 a number of openings, between the numerous islands and islets into 

 which the elevated limestone ridge has been cut up (Plate 80). Through 

 all these the current flows with considerable velocity (three knots). The 



EAST SIDE OF FULAXGA. 



interior of the basin is full of islets and of rocks, mushroom-shaped or 

 dome-shaped, all deeply undercut and all consisting of the same elevated 

 limestone of which the outer ridges ai'e composed (Plate 81). These 

 islets and rocks are of all sizes and shapes, some of them nearly half a 

 mile in length ; and they are found in everv part of the basin (Plates 

 83, 84j. The greatest depth of the interior basin is ten fathoms, with 

 an average of five to six. 



Although the general appearance of Fulanga is much like that of an 

 extinct crater, yet its formation is due to other than volcanic agencies. 

 The whole of the area of Fulanfja must formerlv have been covered by 

 a bed of raised coralliferous limestone. The lower parts of the eastern 

 face of this elevated flat became cut up into islands and islets, allowing 

 the passage of the sea, and it has little by little eaten into the body of the 

 elevated limestone, forming an extensive inner basin four miles in length 



