421 
The atolls and allied coral-islands, resting on truncated and 
submerged islands formerly belonging to the Sunda Land. 
The southernmost, shallowest portion of Strait Macassar is sepa- 
rated on the north from the deeper part of that strait by two groups 
of coral-islands named the Kalu Kalakuang-islands and the Laars 
shoals and again on the south-east from the Flores Sea, by two 
other groups of coral-islands and atolls’), viz. the Paternoster- and 
the Postiljon-islands (Fig. 3). As to their structure they display a 
striking similarity. 
1. The group of the Kalu Kalukwang islands. All of them are 
coral-islands. Most of them are rooted on the rim of a bank, which 
is rather flat, and lies on an average 20, nowhere more than 40 fathoms 
below the sea-level. Three soundings indicating depths of resp. 66, 
90, and more than 100 fathoms, point to a division of the bank 
into two parts by a narrow deep strait. 
All around the bank, which lies about 40 fathoms deep, the sea 
rapidly increases in depth from the edge of the bank. Upon this 
edge a coral-reef has grown up, which has been interrupted in many 
places. On the northern half of the bank this reef reaches the 
surface of the sea in many places; on the southern half this is 
not the case. Independent of the marginal reef, there arise here and 
there reef-structures from the upper surface of the bank as well, 
reaching the surface of the sea in some places. On the extreme northern 
part of the bank the reef-structures are arranged in the shape 
of a ring, thus forming a “faro” or atollon. The Kalu Kalukuang 
islands make up a composite atoll, the ring not being com- 
pletely closed, but, especially in the southern parts, being broken over 
not quite endorse the pronouncement made in the same paper on page 881: “no shelf, 
no barrier-reef.” Even the reverse sometimes appears to be true, as no barrier- 
reef was formed along the Sunda Land in the South China Sea in spite of the 
presence of an extensive shelf, whereas in Strait Macassar, where a shelf was 
absent, a perfect barrier-reef has been developed. No more can | share the writer’s 
opinion (p. 893) that the mode of development of barrier-reefs in the East-Indian 
Archipelago affords “fresh evidence to disprove Darwin’s theory according to which 
barrier-reefs have taken their origin from fringing reefs”. In my opinion Darwin’s 
theory is supported by the mode of development of these reefs, which can only 
strengthen my conviction that ‘‘without subsidence of the lard or rise of the 
sea level strengthen my conviction (which comes to the same) no true barrier- 
reefs and no atolls can originate”. 
') Our knowledge of these coral-islands is still very insufficient. Renewed surveying 
may yield surprising results, as was the case with the latest survey of the islands 
of the Tukang besi group in the year 1916 and of the atoll of the Zandbuis-banks 
in the year 1910. 
