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Ag at sia ——Ao — 
AGASSIZ: FIJI ISLANDS AND CORAL REEFS. 89 
into the fringing reef flats. There are two important passes on the 
southeastern face,’ the Tongan and the American Passages. The latter 
is a narrow tongue of the ocean cutting into the eastern face of the 
slope of the atoll with over 100 fathoms in depth, and opens into a 
wide deep submarine valley extending westward into the heart of the 
eastern lagoon. The Tongan Pass is a similar, but much shallower and 
shorter, tongue of the ocean. On the western side the Andiwathe Pass 
NORTHEAST POINT OF VANUA MBALAVU. 
leads into a long deep lagoon formed by the outer reef and the west 
coast of Vanua Mbalavu. This western lagoon is connected on the 
south with the principal lagoon to the east of the island by a narrow 
and shallower passage over the fringing reef north of Malatta Island, 
and on the north by the passages leading round Ngillangillah Island into 
the passage of that name opening through the northwestern horn of the 
VANUA MBALAVU, LOOKING WEsT. 
outer reef, and which extends, gradually widening eastward, along the 
northern shore of Vanua Mbalavu until it opens beyond Avea Island 
into the large eastern lagoon. Along the northern face of the lagoon 
are situated Avea and Sovu Islands. About two miles from the 
1 An exception to the usual rule, that entrances to lagoons are on the lee side. 
