874 Proceedings of the Royal Society 
Liversidge* has described a similar rock brought by Commodore 
Goodenough from the New Hebrides. It contained small fragments 
of coral and shell, which gave it the appearance of a bone breccia 
from a cave deposit ; but the mode of its occurrence is not stated. 
I should add that in one locality small patches of a fibrous calcite 
about an inch in thickness encrusted the surface of the reef-flat 
near the base of the cliff. 
Ugi Island . — This island is fringed by shore-reefs of varying 
width, which are most extensive on the north-west coast, and are 
absent or broken up in Selwyn Bay. Broad belts of recently 
formed land, strewn with coral and shells, edge the reef-flats. On 
the east coast, the shore-reef encloses a long narrow lagoon, a mile 
in length, and possessing a depth of 10 fathoms and under. In the 
shore-reef on the south coast there is a small circular basin or 
lagoon, about 100 yards across and 6 fathoms in depth, which is 
approached by a narrow entrance, and would make a good boat- 
liarbour. f It is worthy of remark that this island has a rude 
crescentic shape, which it has only assumed during the last hundred 
feet or so of elevation. The small coral island of Biu, which lies 
about 2 miles to the northward, and is included within the same 
100 fathom line, is fringed by shore-reefs. It is about 1J miles in 
length, and may be briefly described as a patch of coral reef which 
has been upheaved about 100 feet above the sea, and is still girt by 
living reefs. In its central elevated portion I found a chalky 
coral limestone. 
Rua Sura Atoll . — This small atoll, which lies 2|- miles off the 
north coast of Guadalcanar, has an elongated shape, and is about 
3 miles in length. Three wooded islets have been formed on its 
south side ; but the remainder of the circumference of this atoll is 
either just awash at low tide, or is covered by less than a fathom of 
water. The actual depth of the lagoon was not ascertained; its 
depth, however, must be considerable, since casts of as much as 
37 fathoms failed to reach the bottom. The soundings taken out- 
* Vide a paper on the Composition of some Coral Limestones, &c., from the 
South Sea Islands, read before the Royal Society of N.S.W., October 6, 1880. 
f These “ holes ” in the shore-reefs are not uncommonly found in other 
islands of this group. They are often termed “boat-harbours,” when access- 
ible ; and are usually 100 to 150 yards across, with depths of 20 fathoms and 
under. 
