176
WILLIAM MACNAE
passages emerging on the mounds. Some of these crabs will be the
same species that occur in the nypa swamps, but they tend to be
reticent, indicating their presence by the form of the burrow entrance
and of the pseudofaecal pellets lying around. They are rarely seen a t
low tide during daylight hours.
Macrophthalmus depressus and M . paci$cus Dana may be abundant
in the sandy bottoms of the shallower creeks at this level.
Water lies around on the surface in shallow pools with little low
mounds of mud emerging. These pools are occupied by several small
crabs of which the males often sit around on the tiny eminences
displaying and feeding. The females tend to remain closer to the edge
of the water in the little pools. The genus characteristic of this sort of
situation is Ilyoplax. I n Malaya I . dekmani (de Man), I. lingulata
Rathbun, I. obliqua Tweedie, and I . punctata Tweedie are all common
but tend to be local.
Tweedie (1950a) has suggested that several of these species of
Ilyoplax are restricted in their distribution, a result of a possibly
abbreviated life history taking place in the vicinity of the pools where
they have been found. Tweedie found all sizes of crabs in such pools.
My own collections and observations, limited as they are, lead me t o
agree with this opinion.
Paracleistostoma depressum de Man, P. microcheirum Tweedie and
P. longimanum Tweedie, Tylodiplax tetratylophorus de Man and Utica
borneensis de Man are other small crabs which may be found in this
sort of environment.
I n Sarawak I found blue-clawed Ilyoplax spinimera Tweedie and
another Ilyoplax sp. with pink-red claws living almost but not quite
sympatrically, the former in wetter places, the latter in drier mounds.
Ilyograpsus paludicola (Rathbun) is a little carnivorous grapsid,
present but never very common in the bruguiera and drier rhizophora
forests throughout the Indo-west-Pacific. Clistocoeloma merguiense de
Man may also occur at this level.
Species of Uca are common in clearings and a t the edges of the
bruguiera forests and ceriops thickets. U . bellator, U . gaimardi
(H.M.-Edw.), U . chloro~hthalmus (H.M.-Edw.), U . manii (Rathbun),
U . rosea (Tweedie) and others are characteristic. Each species tends to
be restricted to one geographical subdivision of the area. U . gaimardi
is African, U . manii and U . rosea are Malaysian, U . chlorophthalmus is
Micronesian, U . bellator is Australian.
Of molluscs, the brackish water ellobiids, mentioned above, persist
and are joined by more marine species of other families : e.g. a species
of Haminea, Terebralia palustris L. (Fig. 55F), T. sulcata Born. (Fig.
WILLIAM MACNAE
passages emerging on the mounds. Some of these crabs will be the
same species that occur in the nypa swamps, but they tend to be
reticent, indicating their presence by the form of the burrow entrance
and of the pseudofaecal pellets lying around. They are rarely seen a t
low tide during daylight hours.
Macrophthalmus depressus and M . paci$cus Dana may be abundant
in the sandy bottoms of the shallower creeks at this level.
Water lies around on the surface in shallow pools with little low
mounds of mud emerging. These pools are occupied by several small
crabs of which the males often sit around on the tiny eminences
displaying and feeding. The females tend to remain closer to the edge
of the water in the little pools. The genus characteristic of this sort of
situation is Ilyoplax. I n Malaya I . dekmani (de Man), I. lingulata
Rathbun, I. obliqua Tweedie, and I . punctata Tweedie are all common
but tend to be local.
Tweedie (1950a) has suggested that several of these species of
Ilyoplax are restricted in their distribution, a result of a possibly
abbreviated life history taking place in the vicinity of the pools where
they have been found. Tweedie found all sizes of crabs in such pools.
My own collections and observations, limited as they are, lead me t o
agree with this opinion.
Paracleistostoma depressum de Man, P. microcheirum Tweedie and
P. longimanum Tweedie, Tylodiplax tetratylophorus de Man and Utica
borneensis de Man are other small crabs which may be found in this
sort of environment.
I n Sarawak I found blue-clawed Ilyoplax spinimera Tweedie and
another Ilyoplax sp. with pink-red claws living almost but not quite
sympatrically, the former in wetter places, the latter in drier mounds.
Ilyograpsus paludicola (Rathbun) is a little carnivorous grapsid,
present but never very common in the bruguiera and drier rhizophora
forests throughout the Indo-west-Pacific. Clistocoeloma merguiense de
Man may also occur at this level.
Species of Uca are common in clearings and a t the edges of the
bruguiera forests and ceriops thickets. U . bellator, U . gaimardi
(H.M.-Edw.), U . chloro~hthalmus (H.M.-Edw.), U . manii (Rathbun),
U . rosea (Tweedie) and others are characteristic. Each species tends to
be restricted to one geographical subdivision of the area. U . gaimardi
is African, U . manii and U . rosea are Malaysian, U . chlorophthalmus is
Micronesian, U . bellator is Australian.
Of molluscs, the brackish water ellobiids, mentioned above, persist
and are joined by more marine species of other families : e.g. a species
of Haminea, Terebralia palustris L. (Fig. 55F), T. sulcata Born. (Fig.