~ aaaiins 
AGASSIZ: FIJI ISLANDS AND CORAL REEFS. 5ST 
enclosing a triangularly shaped lagoon, with a greatest depth of 21 
fathoms. The length of the southern reef flat is a little over ten miles, 
that of the northern face about nine miles, and that of the western and 
northwestern faces connecting them is five miles. There are three pas- 
sages on the western and northwestern faces, and one through the north- 
ern face. The bottom of the lagoon, between the reef patches and heads, 
is covered with coralline alge and with coral sand. There are many 
large heads scattered along the inner edge of the northern reef flat, and 
on the extension of the western extremity of the island. 
Namuka. 
Plate 22. 
We did not visit Namuka, but steamed near enough to the island to 
recognize its distinctive features. It is a narrow, undulating ridge, four 
miles long, rising to a height of 240 feet; it is composed of elevated 
limestone. On the southern and western faces there are deep bays, or 
incipient sounds, which, if extended, would divide the island into a 
number of islets. The island is surrounded by a fringing reef off the 
southwestern extremity, and off the eastern point of the island. Be- 
tween these points an outer reef extends off the south coast, forming a 
narrow and shallow lagoon full of heads, with five fathoms at its deepest 
point. On the northern face the western part of the lagoon is deeper, 
having thirteen fathoms. The horns of the outer reef of the northern 
and western faces are connected by broken patches and heads which 
form the harbor of Namuka. 
About three and a half miles northeast from the entrance to Namuka 
Harbor lies Wilkes Reef (Plate 22), a flat a little over halfa mile in 
length, dry at low water, with cutlying rocks and banks within the sur- 
rounding 100 fathom line. 
Yangasa. 
Plates 22, 22°, Figs. 8, 9, and Plates 90-93. 
The cluster of Yangas4 (Plate 22) consists of four islands and numer- 
ous rocks and islets, all of which are composed of elevated limestone. 
The largest island of the group, Yangasé Levu, is nearly two miles in 
length and about half a mile wide. Its shores are formed of precipitous 
cliffs, which surround the whole island ; they are deeply undercut at the 
base, perhaps more than any other island we have seen in Fiji. The 
