FAUNA AND FLORA O F MANGROVE SWAMPS
210
ring under leaves and driftwood or under the trailing plants in the zone
of samphires and Sesuviunz.
Shells of species of Syncera (= Assimiizea) are common ton at all
levels up to the landward fringes. I n Australia specimens of Salinator
are common and also of Bembicium.
No work other than taxonomic has been done on this group of what
v011 Martens used to call submarine snails. Their requirements are
neither known nor understood. Their life cycles are not well known
and have been rarely commented on. Morton (1955), discussing the
evolution of the Ellobiidae, sees in them a group close to the stem of
the pulmonates and places them in a position a t the base of the pulmonate stem analogous to Actaeon at the base of the opisthobranchs.
Morton would consider the estuarine and mangal-living species and
genera more primitive than those he calls the marine intertidal, or
coastal terrestrial or inland terrestrial forms. It is inherent in Morton's
thesis that the pulmonates came from the sea by way of the mangal in
the tropics or salt marshes in temperate regions.
Equally little is known of the requirements of the bivalves living in
the mangal. Glaucomya and Laterntila are typical mud living forms
living in Coccoons of a sort among the rootlets of the mangroves of the
seaward fringe. Potyrnesoda (Geloina) and Batissa are representatives of
freshv, ater families which have presumably become euryhaline.
V I I . GEOGRAPHICAL DISTRIBUTION
A. E'xtrutropicul extensions of naangroves and their associated fauna
Mangroves reach their greatest luxuriance, both in number of
species and in area covered by them within a few degrees of the Equator
in countries where rain falls abundantly in all seasons. North and south
of this belt one season becomes dry, the result of the shifting of the
intertropical front and of the monsoon effects of the Asiatic land mass.
Surprisingly this change does not affect the constitution of the mangrove
forests, although i t may and often does affect the way in which not only
individual trees develop but also the way in which they are distributed
in the association. As the length of the dry season and its intensity
increases changes occur as described above (pp. 91-1 14).
Mangroves extend beyond the tropics both northward in Asia and
southward in Africa, Australia and New Zealand. Except in eastern
Asia the manner of falling out of species is similar.
On the African coast Sonneratia alba and Heritiera littoralis are quite
common a t Inhambane (lat. 24"s.) but do not occur south of this.
210
ring under leaves and driftwood or under the trailing plants in the zone
of samphires and Sesuviunz.
Shells of species of Syncera (= Assimiizea) are common ton at all
levels up to the landward fringes. I n Australia specimens of Salinator
are common and also of Bembicium.
No work other than taxonomic has been done on this group of what
v011 Martens used to call submarine snails. Their requirements are
neither known nor understood. Their life cycles are not well known
and have been rarely commented on. Morton (1955), discussing the
evolution of the Ellobiidae, sees in them a group close to the stem of
the pulmonates and places them in a position a t the base of the pulmonate stem analogous to Actaeon at the base of the opisthobranchs.
Morton would consider the estuarine and mangal-living species and
genera more primitive than those he calls the marine intertidal, or
coastal terrestrial or inland terrestrial forms. It is inherent in Morton's
thesis that the pulmonates came from the sea by way of the mangal in
the tropics or salt marshes in temperate regions.
Equally little is known of the requirements of the bivalves living in
the mangal. Glaucomya and Laterntila are typical mud living forms
living in Coccoons of a sort among the rootlets of the mangroves of the
seaward fringe. Potyrnesoda (Geloina) and Batissa are representatives of
freshv, ater families which have presumably become euryhaline.
V I I . GEOGRAPHICAL DISTRIBUTION
A. E'xtrutropicul extensions of naangroves and their associated fauna
Mangroves reach their greatest luxuriance, both in number of
species and in area covered by them within a few degrees of the Equator
in countries where rain falls abundantly in all seasons. North and south
of this belt one season becomes dry, the result of the shifting of the
intertropical front and of the monsoon effects of the Asiatic land mass.
Surprisingly this change does not affect the constitution of the mangrove
forests, although i t may and often does affect the way in which not only
individual trees develop but also the way in which they are distributed
in the association. As the length of the dry season and its intensity
increases changes occur as described above (pp. 91-1 14).
Mangroves extend beyond the tropics both northward in Asia and
southward in Africa, Australia and New Zealand. Except in eastern
Asia the manner of falling out of species is similar.
On the African coast Sonneratia alba and Heritiera littoralis are quite
common a t Inhambane (lat. 24"s.) but do not occur south of this.