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AGASSIZ: FIJI ISLANDS AND CORAL REEFS. 127 
haps assume from the information I have gathered and from an exami- 
nation of the charts, that neither they nor the smaller islands and reefs 
in the Lau Archipelago, which have been passed by, present any features 
which are likely to throw much additional light on the results obtained 
from the examination made by the “ Yaralla.” The area between the 
Yasawa group and the north shore of Viti Levu (Plate 3) has not been 
systematically surveyed. All we know is that it is full of coral patches, 
undoubtedly the eastern extension of the patches to the northwest of 
Nandi waters towards the Yasawa group. How far west of Charybdis 
Reef the extension of the deep water bay north of Vatu i ra Channel 
reaches is not known. Its northern and eastern limits off Vanua Levu 
are well defined on the charts (Plate 3). It is interesting to note that 
a very steep slope — fully as steep as any of the sea faces off the reefs or 
smaller islands of Fiji, or as steep as the sea faces of the great barrier 
reef off the south coast of Viti Leva —runs off the west side of Vanua 
Levu from the Makongai Channel beyond Yendua Island (Plate 3), and 
off the east side of Viti Levu from the horn of the reef north of Ovalau 
to opposite Charybdis Reef. Yet on this steep face the corals form 
only scattered patches over the surface of the flats, extending between 
the shore lines toward the 100 fathom line, — patches and stretches 
which are separated by wide areas in which the bottom is full of heads 
of rocks similar to those of the adjoining shores. 
Charybdis Reef and the extensive reef on the southwest side of Vatu 
ira Channel (Vatu i ra Reef), represent probably the eroded summits of 
a more or less circular island and of an elongated ridge, on the outer 
edges of which coral patches have found a footing, and of which Vatu i ra 
Islet (one hundred feet high) is the only remnant. The lagoon varies in 
depth from twenty-two to twenty-seven fathoms, “ with several passages 
into it through which the tide runs strongly.” Charybdis Lagoon is 
full of rocks and patches its average depth is about twenty fathoms ; 
its western edge is open, with rocks scattered along its face. 
An extensive fringing reef skirts the north shore of Viti Levu, which 
disappears within reach of the influence of Ba River. There is a 
wide navigable channel between it and the broad outer barrier reef 
patches, which resemble those off the east coast of Viti Levu, south of 
Moturiki Channel. 
I have not examined the shores of Vanua Levu, but according to 
Horne’ and from some verbal information relating to the barrier 
1 John Horne, “ A Year in Fiji,’ London, 1881, pp. 167, 168. Horne says that 
on the southwest side of Rambe a reef has been elevated twenty feet, and that the 
