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AGASSIZ: FIJI ISLANDS AND CORAL REEFS. 141 
On Plate 22°I have a series of hypothetical figures to illustrate the 
changes 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 
represented 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 submarine denudation being 
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 underlying 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 harbor of Leyuka, upon the platform of submarine erosion consisting 
of voleanic rocks, as represented by the dotted lines in those Figures. 
Figures 1 to 5 represent the hypothetical outlines of volcanic islands. 
Figure 1, that of Nairai, 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 Nairai 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 (Makongai and Wakaya). 
Figure 4 represents Mbengha, 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 North 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 6, Tuvana i ra, 
