PROFESSOR W. J. SOLLAS, 



against the passage of Te Buabua, which is separated from the next passage on the 

 south, Te Ava Mateika, by a very short interval of reef. Beyond Te Ava Mateika 

 it bounds the attenuated " neck" of the island, extending all round this without a 

 break, and northwards as far as Te Ava Fuagea, where it is inflected into the lagoon, 

 bounding like a thick lower lip the narrow and deep channel of Fuagea, which is 

 nowhere less than 23 fathoms in depth. The lagoon is very shallow within the 

 " neck," and floored by a thin solid crust ; the streams of sea-water which drain it 

 between tides carry with them abundant sand comjDOsed of foraminifera. 



The " nose " is a remarkable feature of the atoll, its root being a broad expanse of 

 tide-washed reef, and it extends out into the ocean as a growing bank of coral, sub- 

 merged to a depth of 7 fathoms for the most part, but rising near its extremity into 

 the reef Te Akau Fuafatu, which reaches to within 3 fathoms of the surface. This 

 tendency to grow outward into the ocean is again seen further north in Te Afua Sari, 

 which forms a sort of brow-ridge to the profile, and bounds a second deep and narroAv 

 passage, Te Ava Tebuka. 



The prevailing winds are easterly (as is the set of the ocean currents), so that the 

 most irregular part of the reef is on the leeward side. 



The floor of the lagoon is tolerably even, gradually deepening from the shore to an 

 average depth of 20 or 25 fathoms, attaining in four cases an extreme depth of 

 30 fathoms, and rising in many others to form slightly submerged shoals, oreven reefs 

 awash, of which Te Akau Tuluaga in the middle of the lagoon is the largest ; this dries 

 to 4 feet, and having landed on it, I collected from it foraminiferal sand and molluscan 

 shells, as well as dead and living coral. 



The submarine configuration of the atoll was very fully investigated by Captain 

 Field ; in addition to numerous deep-sea soundings taken all round the island, four 

 profiles were obtained by as many series of soundings run from the seaward face of 

 the reef outward. The successive soundings of a series were separated by the follow- 

 ing intervals : — 



For a depth between — 40 flithoms every 10 yards. 



40— 70 

 70—100 

 100—150 

 150 — 200 

 200—300 

 300—400 

 400—500 

 500—600 

 000—700 

 700—800 



20 

 30 

 40 

 50 

 (50 

 70 

 80 

 90 

 100 

 200 



The results are shown on fig. 3, reduced from profiles plotted to true scale, from 



