7
specimens which entered the inland sea as larvae in the first
days of October 1944. Sooner or later these veligers preci
pitated and metamorphosed to young bivalves. In this stage
they hibernated and in the following spring growth set in
rapidly. Thus in about a year's cycle the little clams attained
about 50 mm length which is about one third of their possible
maximum size.
Two carapaces of the common crab (Carcinides maenas L.
of resp. 43 and 38 mm breadth were also collected. It is
possible that these animals were actually bred in the Wal
cheren inland sea, but in the case of such vagrant and migra
tory creatures it will always remain uncertain whether they
were inhabitants from their birth or may have entered the
area much later in the adult stage.
Still rarer ware the records of starfish (Asterias rubens L.)
which was observed only once. The common periwinkle
Littorina littorea L.) has not been recorded.
The marine phase in the history of Walcheren has not led
to a condition in which the fauna of the flooded area was
representative of the sea fauna in the immediate vicinity of
the island, i.e. the fauna of the Oosterschelde, the Wester-
schelde or the North Sea off Westkapelle and Domburg. For
that purpose the time during which the invasion lasted was
far too short and the communication between the inland sea
and the exterior too fragmentary, so that only a fraction of
the number of species had the opportunity to enter. The
marine fauna of Walcheren therefore was composed of species
which either could swim actively or which had pelagic larvae.
Animals with a slow rate of locomotion such as various gastro
pods, had little or no chance to take possession of the new
habitat.
