of Edinburgh, Session 1885 — 86 . 
871 
coral islands which, commenced their growth as submerged flat-topped 
reefs resembling in their character the present condition of the 
neighbouring Lark Shoal. These reefs were subsequently elevated 
about 70 feet above the sea, and the islands have since assumed an 
atoll structure. From their arrangement and from the depth of 
water separating them from the adjacent islands,* it may be inferred 
that these coral islands are based on three submerged peaks which 
lie at some unknown distance below the surface. They are included 
within the same 100 fathom line. On the weather or eastern sides 
the submarine slope is gradual for the first few fathoms ; it then 
descends to the depth of 100 fathoms at an angle rather in excess of 
20°. On the lee sides the submarine slope descends usually at a 
smaller angle. 
Malaupaina, the southernmost of these islands, is about 3J miles 
in length and rather over half a mile in breadth. Its lee or western 
half, which is mostly occupied by mangrove swamps that are over- 
flown by the sea at high water, contains two lagoons opening by 
narrow entrances on the west coast. A low bank, raised 2 to 3 feet 
above the high tide level and from 20 to 100 paces in width, 
intervenes between the sea and the mangrove swamps within, and 
forms the western margin of the island : it is composed, sometimes 
of sand, at other times of shells and loose coral fragments, and 
occasionally of coral rock ; whilst its surface supports such trees 
as the casuarine, pandanus, and cocoa-nut palm. The weather or 
eastern portion of the island may be described as a broad wooded 
tract elevated between 10 and 15 feet above the sea. Between the 
tide marks on this coast, there is an extensive flat of coral rock 
traversed by deep fissures and narrow gulleys, running at right 
angles to the trend of the coast, in which rushes to and fro the wash 
of each roller that breaks on the edge of the reef. Situated towards 
the interior of the island, and separated by the northern lagoon, are 
two low hills of coral limestone,! the level summits of which are 
elevated from 50 to 70 feet above the sea. Of the two lagoons, the 
southern is the deepest : it has a depth of 9 fathoms, and is shut in 
* A cast of 400 fathoms to the west and another of 260 to the north-east 
failed to reach the bottom. 
+ Hand specimens from one of these hills were in part chalky. Vide my 
paper on the “Calcareous Formations,” Trans. Edin. Boy. Soc., vol. xxxii. 
part 3, pp. 563, 575. 
