AGASSIZ: FIJI ISLANDS AND CORAL REEFS. 49 
liferous limestone rock, and are the remnants of the former land mass 
once covering the area of the atoll of Ngele Levu. 
Nuku Mbasanga. 
Plates 18, 22%, Fig. 18, and Plate 108. 
We skirted along a part of the southwestern edge of Nuku Mbasanga 
atoll (Plate 18). The atoll is oblong, a little over two miles long, open 
to the northwest, where the reef flats are broken up into numerous 
coral heads. Within the broad reef flats are a small sandy cay, Nuku 
Mbalate on the western face of the atoll, and the islet of Nuku Mbasanga 
(Plate 108), the shores of which are covered with coral beach rock, or 
patches of elevated reef rock, judging from the character of the negro- 
heads which crop out on the western side. Both the islands are covered 
with coacoanuts and shrubs. 
There is every reason to believe that the islands of the Nuku Mba- 
sanga group are the remnants of an island composed of elevated lime- 
stone, which has been denuded and eroded to its present condition, and 
partly covered, as Wailangilala has been, with coral sand. 
Nukusemanu and Nanuku Reefs. 
Plates 18, 103-107. 
To the eastward of Budd Reef, and separated from it by a channel 
about nine miles wide, is situated an elongated, angular, irregularly 
shaped atoll, terminating at its southern extremity in a long ridge of 
reef flats called the Nanuku Reef. These send out spurs, the extension 
of which connects with the Nukusemanu Reef and encloses a lagoon 
fully twenty-four miles long and from two to six miles broad. The 
greater part of the eastern face of the reef is not awash, being made up 
of a long series of coral reef patches, with from one to six fathoms of 
water, with deeper water between it and the extension of the Nanuku 
Reef. A tongue of the ocean runs westward from 118 fathoms in the 
gap separating the extremities of the reefs, rising to a ridge with five 
to ten fathoms, separating it from a deep pool with as much as forty-six 
fathoms near the eastern face of the central part of the western reef flat 
of Nanuku Reef. Only an occasional reef patch rises to the surface on 
that face. On the northeast horv is situated Nukusemanu Island, a 
small sand key covered with cocoanuts. On the northwest face the 
Nukusemanu Reef flats are seen to be well covered with flourishing coral 
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