180
WILLIAM MACNAE
their saucer- or bowl-shaped burrows mainly a t this level and hold
territory here. Only P. schlosseri extends to the inner parts of the
mangal and then only at high water.
Around the bases of the small bushes of the pioneer mangroves, or
around piles or posts driven into the soil, tiny crabs, such as species of
Ilyoplax, Leiopecten sordidulum Kemp, Metaplax elegans de Man and
others, cluster and the species of Ilyoplax
may make their small
burrows. Burrows of a species of Upogebia become common and may
be used as refuges by these small crabs and by species of Paracleistostoma.
As the ground becomes firmer under the older trees, particularly
where the area has been to some extent cleared, or elsewhere where
sunny patches occur on the forest floor, another series of crabs take
over. I n western Malaya and peninsular Thailand there is Uca rosea
(Tweedie), in Borneo U . rhizophorae Tweedie, and with them the
smaller blue-speckled, orange-clawed U . triangularis (A.M.-Edw.)-its
var. variabilis de Man is present in Borneo, the typical form in western
Malaya.
The soil a t this level is riddled with burrows of an Upogebia and
these burrows are the refLiges of a host of tiny crabs. Juvenile king
crabs, Tachypleus gigas (Muller) and Carcinoscopius rotundicauda
(Latr.) may also be found partially buried in the mud. Adults of both
may be seen in pairs, the smaller male riding on the back of the larger
female as the tide leaves, while they swim downwards with the
retreating water.
Water snakes, most commonly Cerberus rhynchops, seek for crabs
in their burrows while the tide is in and curl up in the shade of the
trees during low tide periods.
Snails, chiefly Xyncera brevicula and a species of Haminea that
produces a purple dye, are often common on the surface of the mud
under the shade of the trees. Telescopium telescopium and T . mauritsi
crawl around in the wetter runnels. Cassidula auris-felis and C. mustelkina are also common on the surface of the mud as on the bases of the
trunks of the trees. C. angulifera (Fig. 54B) is common in Australia.
I n some localities where the mass of nutritive rootlets of Avicenizia
or of Sonneratia give a degree of stability to the shore, large populations
of bivalves of the genera Glaucomya and Laternula live in coccoons
made by themselves. They may, in fact, be so common as to give the
surface a peculiar pock-marked appearance which results from the
activities of their siphons.
Running around among the pneumatophores in Malaya and in
Sarawak are two small crabs : Nannosesarma minuta and Clistocoeloma
merguiense.
WILLIAM MACNAE
their saucer- or bowl-shaped burrows mainly a t this level and hold
territory here. Only P. schlosseri extends to the inner parts of the
mangal and then only at high water.
Around the bases of the small bushes of the pioneer mangroves, or
around piles or posts driven into the soil, tiny crabs, such as species of
Ilyoplax, Leiopecten sordidulum Kemp, Metaplax elegans de Man and
others, cluster and the species of Ilyoplax
may make their small
burrows. Burrows of a species of Upogebia become common and may
be used as refuges by these small crabs and by species of Paracleistostoma.
As the ground becomes firmer under the older trees, particularly
where the area has been to some extent cleared, or elsewhere where
sunny patches occur on the forest floor, another series of crabs take
over. I n western Malaya and peninsular Thailand there is Uca rosea
(Tweedie), in Borneo U . rhizophorae Tweedie, and with them the
smaller blue-speckled, orange-clawed U . triangularis (A.M.-Edw.)-its
var. variabilis de Man is present in Borneo, the typical form in western
Malaya.
The soil a t this level is riddled with burrows of an Upogebia and
these burrows are the refLiges of a host of tiny crabs. Juvenile king
crabs, Tachypleus gigas (Muller) and Carcinoscopius rotundicauda
(Latr.) may also be found partially buried in the mud. Adults of both
may be seen in pairs, the smaller male riding on the back of the larger
female as the tide leaves, while they swim downwards with the
retreating water.
Water snakes, most commonly Cerberus rhynchops, seek for crabs
in their burrows while the tide is in and curl up in the shade of the
trees during low tide periods.
Snails, chiefly Xyncera brevicula and a species of Haminea that
produces a purple dye, are often common on the surface of the mud
under the shade of the trees. Telescopium telescopium and T . mauritsi
crawl around in the wetter runnels. Cassidula auris-felis and C. mustelkina are also common on the surface of the mud as on the bases of the
trunks of the trees. C. angulifera (Fig. 54B) is common in Australia.
I n some localities where the mass of nutritive rootlets of Avicenizia
or of Sonneratia give a degree of stability to the shore, large populations
of bivalves of the genera Glaucomya and Laternula live in coccoons
made by themselves. They may, in fact, be so common as to give the
surface a peculiar pock-marked appearance which results from the
activities of their siphons.
Running around among the pneumatophores in Malaya and in
Sarawak are two small crabs : Nannosesarma minuta and Clistocoeloma
merguiense.