PAUMOTU GROUP. 329 
day was spent on the island. Near the place where we landed, there 
has been a channel to the small lagoon in the centre of the island, and 
there is another of a similar character on the opposite side. They 
were both dry, and the sea-water can only communicate with the 
lagoon at very high tides. From our observations of the day, the 
usual neap tide is three and a half feet, and it would give high water 
at full and change of the moon, at 2 p. m. 
SECTION OF CORAL ISLAND. 
There are many blocks of compact coral, just at high water mark, 
quite black on the outside, but on fracture they showed the white 
coral. The white coral shelf over which the sea flows at high water 
was two hundred feet broad, the low water falling two feet below its 
surface : it is quite level, but there are many holes and large longi- 
tudinal cracks in it. On this lies the compact coral above spoken 
of, extending beneath the coral sand. It is about ten or twelve feet 
wide. The coral sand beach above the compact layer has eight feet 
perpendicular rise, and lies at an angle of 47°. On the top of this 
are small pieces of coral, which have been thrown up by the sea, 
around the roots of trees and shrubs, growing to the height of from 
fifteen to twenty feet. We found the water in the lagoon quite salt, 
and very warm. Its bottom for a long distance was filled with a fine 
deposit of calcareous mud, about six inches in depth. The water 
had apparently evaporated from the lagoon, and to the taste was 
much salter than the ocean. Purslain (Portulacca) was found 
growing in a thrifty state in this deposit, Where the lagoon was 
deeper, some fine specimens of corals were observed and obtained. 
No traces of inhabitants were perceived on this island. The state 
of nature in which the birds were found, and other indications, 
gave proof that it had not been inhabited, at least for some time. 
There were a great many sharks, both in the lagoon and outside, 
which were so ravenous that they would bite at the oars. It was by 
no means pleasant to have to swim through the surf to the boat 
with them so numerous around us. 
s:j 
