226
WILLIAM MACNAE
scopiuna telescopium, both of which have been recorded as uncommon
in Madagascar become a notable feature of muddy shores Salinator
burmana reaches its most western extension along this coast as do
brackish water bivalves of the genus Polymesoda (Geloina).
On this coast the Malayan mangroves begin t o appear. Avicennia
alba and A . oficinalis are conspicuous. Xonneratia apetalu is restricted
to the Malabar coast where it occupies the niche utilized by S. alba in
eastern Africa.
2. Divisions 2 and 3. The Indo-Malayan region
The region from Ceylon and the Coromandel coast of eastern India
along the shores of the Bay of Bengal into South East Asia and
including the largest islands of Indonesia, Sumatra, Java and Borneo
and their satellite islands constitutes the centre of distribution of both
the plants and animals of the mangal. Yet within this large region
differences can be recognized and the whole area subdivided.
The subdivisions follow, roughly, the three major drainage areas of
the Pleistocene subcontinental peninsula of Sundaland (Fig. 75). My
second division follows the western coastline and the portions of the
foundered coastal plains behind this, the third division follows the
north-eastern coastline and the associated foundered portion, the fifth
division listed on p. 230 comprises the eastern shores of Sundaland
together with Celebes and the Molluccas.
There is almost no floral justification for making these subdivisions
but there is considerable faunal justification.
One of the few plants which may justify this is Avicennia lanata, a
species common among the mangroves of eastern Malaya from Pahang
southwards. Watson (1928) is explicit that it does not occur west of
Singapore.
Another genus with this split in distribution is Aegialitis of which
Ae. rotundifolia occurs on the northern shore of the Bay of Bengal and
a species of Aegialitis although no longer occurring has been recorded
as fossil in Sarawak (Muller, 1964). Ae. annulata extends from eastern
Indonesia to Australia.
The separation of the second and third divisions was first hinted at
in Smith's (1926) monograph of the sea snakes of the family Hydrophiidae (Tweedie, 1954). I n his descriptions Smith recognized six
species ubiquitous in the Indo-Australian region ; seven restricted t'o
Indo-Burmese shores ; seven from Malaya to the Philippines ; three
were Chinese and fourteen Australian; a further eleven were shared
either between the Indian and Malayan or between the Malayan and
Australian regions. No explanation was given or suggested. Significant
WILLIAM MACNAE
scopiuna telescopium, both of which have been recorded as uncommon
in Madagascar become a notable feature of muddy shores Salinator
burmana reaches its most western extension along this coast as do
brackish water bivalves of the genus Polymesoda (Geloina).
On this coast the Malayan mangroves begin t o appear. Avicennia
alba and A . oficinalis are conspicuous. Xonneratia apetalu is restricted
to the Malabar coast where it occupies the niche utilized by S. alba in
eastern Africa.
2. Divisions 2 and 3. The Indo-Malayan region
The region from Ceylon and the Coromandel coast of eastern India
along the shores of the Bay of Bengal into South East Asia and
including the largest islands of Indonesia, Sumatra, Java and Borneo
and their satellite islands constitutes the centre of distribution of both
the plants and animals of the mangal. Yet within this large region
differences can be recognized and the whole area subdivided.
The subdivisions follow, roughly, the three major drainage areas of
the Pleistocene subcontinental peninsula of Sundaland (Fig. 75). My
second division follows the western coastline and the portions of the
foundered coastal plains behind this, the third division follows the
north-eastern coastline and the associated foundered portion, the fifth
division listed on p. 230 comprises the eastern shores of Sundaland
together with Celebes and the Molluccas.
There is almost no floral justification for making these subdivisions
but there is considerable faunal justification.
One of the few plants which may justify this is Avicennia lanata, a
species common among the mangroves of eastern Malaya from Pahang
southwards. Watson (1928) is explicit that it does not occur west of
Singapore.
Another genus with this split in distribution is Aegialitis of which
Ae. rotundifolia occurs on the northern shore of the Bay of Bengal and
a species of Aegialitis although no longer occurring has been recorded
as fossil in Sarawak (Muller, 1964). Ae. annulata extends from eastern
Indonesia to Australia.
The separation of the second and third divisions was first hinted at
in Smith's (1926) monograph of the sea snakes of the family Hydrophiidae (Tweedie, 1954). I n his descriptions Smith recognized six
species ubiquitous in the Indo-Australian region ; seven restricted t'o
Indo-Burmese shores ; seven from Malaya to the Philippines ; three
were Chinese and fourteen Australian; a further eleven were shared
either between the Indian and Malayan or between the Malayan and
Australian regions. No explanation was given or suggested. Significant