58 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY, 
crest of the highest ridge is flat, and runs ata general level of about 
300 feet. The highest summit, toward the southern end of the island, 
is nearly 400 feet ; off that point there are indications of a terrace at 
about one third the height of the island, as if the elevation of this 
group had taken place at two successive periods. Yangasé Levu seen 
from the west, on the way to Ongea, appears hat-shaped, with a high 
terrace forming the rim. The island of Yangasé Levu is from one to 
two miles distant from the inner edge of the outer reef flat forming the 
eastern horn of the lagoon. Along the western side of the lagoon are 
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YANGASA LEVU. 
situated Navutuira, in the northwest angle of the lagoon, which rises to 
270 feet ; this is connected with the islet of Yuvutha (Plate 90) by a 
long narrow reef studded with mushroom-shaped rocks rising above 
high water mark. The whole of the northwestern part of the lagoon 
to the west of the ship passage on the north face of the outer reef flat is 
also thickly studded with negro-heads and with mushroom-shaped rocks 
_ of all sizes and shapes, which cover the wide reef flat to the west and 
north of Navutuira. The: large mushroom-shaped heads are generally 
on the extension of spits or headlands of the two islands named. 
The crest of Navutuira is undulating, and from its shores rise low 
undercut vertical bluffs. Yuvutha (Plate 90), on the contrary, has a 
conical outline, its highest summit rising to 240 feet ; its vertical shore 
bluffs are higher than those of Navutuira, deeply undercut ; they are 
nothing but the rim of a sound left from the disintegration, denudation, 
and erosion of the adjoining land. Such rims are at a distance readily 
mistaken for the rims of extinct craters. We anchored off the west side 
of Navutuiloma, the most southern of the islands along the west side of 
the lagoon. The small bay on the north face of Navutuiloma resembles 
closely a part of the rim of an extinct crater. But that rim and those 
forming the eastern and western points are entirely composed of ele- 
vated limestone, full of caverns and caves, pits and potholes, many of 
them full of red earth, as is the case wherever elevated limestone is 
met with; it is deeply honeycombed and cut into ridges (Plate 92), 
upon the edges of which rise endless sharp pinnacles and needles. 
This was also the structure and appearance of the inland slope of 
the island where we landed. 
