AGASSIZ: FIJI ISLANDS AND COEAL REEFS. 141 



On Plate 22'' I have a series of hypothetical figures to illustrate the 

 clianges I imagine the islands of Fiji to have undergone from the time 

 of their elevation to the present day. The only type which is not 

 repreisented is that of Koro, which is however sufficiently well shown 

 on Plate 19% Fig. 8. The highest point of Koro occupies a nearly 

 central position, the eastern platform of suhmarine denudation beinf 

 only slightly wider than the western. Koro occupies a position inter- 

 mediate between Makongai and Wakaya (Plate 22^, Figs. 2, 3), where 

 in the one case the widest platform of submarine erosion is situated on 

 the west side, and in the other on the eastern face of the island. 



The dotted lines surmounting the Figures of Plate 22*" indicate the 

 hypothetical islands as they may have appeared after their elevation to 

 the highest point ; the solid lines indicate the heights of the islands as 

 they are at the present day, and the lower dotted lines in Figures 7 to 12 

 indicate the position of the imderlying volcanic rocks which have ele- 

 vated the overlying coralliferous limestones in Figures 7 to 11, while in 

 Figure 12 the volcanic rocks of Vanua Mbalavu are seen to pass under 

 the elevated limestones of Thikombia i lau. 



In Plate 20% Figures 1 to 5, the dotted lines represent the position of 

 the volcanic rocks underlying the recent coral reefs forming the barrier of 

 the hai'bor of Levuka, upon the platform of submarine erosion consisting 

 of volcanic rocks, as reiDresented by the dotted lines in those Figures. 



Figures 1 to 5 represent the hypothetical outlines of volcanic islands. 



Figure 1, that of Xairai, with a narrow barrier reef off the east coast 

 and a wide platform of submarine erosion on the western face, with 

 heads and patches which probably represent higher points of the 

 original Naii-ai as indicated by the dotted lines. Figures 2 and 3 

 represent modifications of a volcanic island having probably in one case 

 its highest point nearest the eastern edge of the lagoon, and in the 

 other nearest the western side of the lagoon (Alakongai and Wakaya). 



Figure 4 represents ^Ibengha, in which there must have been a 

 western ridge, and perhaps also a central ridge, more or less parallel 

 with the two main ridges of Mbengha near the eastern edge of the 

 lagoon. 



Figure 5 represents the continuation of a former great ridge northward 

 from Kandavu towards the Xorth Astrolabe Reef, which has been 

 denuded and eroded into a series of islands now existing in the Great 

 Astrolabe Lagoon. 



Figures 6 to 11 represent the former outlines of islands composed of 

 elevated coralliferous limestone. In the case of Figure G, Tuvana i ra, 



