;
Notes on the
I
Life - History of Planorbis
corneus and Other Freshwater Mollusks
WILLIAM
T.
WEBSTER,
F.
R.
M.
5.
i
•Hi At the previous meeting of
this society
had the pleasure of bringing
I
notice the occurrence of a red
to your form of
Planorbis corneus, and in stating the fact
many
that
freshwater snails cannot live
with the Cypridae. At the made this communication, I did quite know the extent and scope of
in association
time not
I
and my remarks were confew bare facts. I hope, to-
this society,
fined to a night, to
but
go into the matter more fully
there
definite
are
which
still
several
hope
I
to clear
matters
up
in-
some
at
future date. I
do not make any pretensions to being
considered an authority on the subject of freshwater snails
;
tirely centred in their
my
is
is
form has a
value than any other, that
is,
one
and
importance,
very considerable
possibly this red
en-
food for
In this respect the subject
fishes.
of
interest
utility as
being taken respecting this
snail.
have distributed quantities over a wide area, and there is probably little danger now of its becoming extinct. I
summer
I
had the pleasure
of conducting one of your fellows to the
pond where
it
be interested to to find
was found, and you
know
that
we were
the centre. In many cases the hole is quite small, whilst in others the perfora tion is large, and only the outer,
or body, In the early summer these perforations were neatly sealed
whorl remained. all
—quite
for study,
as
perfectly as if done in a turning lathe, and there was nothing to indicate that they had ever possessed
an Later in the season, the sealing becam.- ragged as further erosion took apex.
place.
It is interesting to record that nearly every specimen with a large hole, if lifted carefully by hand, had a young
Sphaermm corneum
On many
attached
to
the
—the bivalve dropped away when was used for
collecting.
carefully examining the tentacles peculiarities are observed.
Some
have both extremely long, slender and well matched. Some have one long and one short the shorter is left or right in;
discriminately.
Some have two very
short
stunted and conical.
few
tentacles,
A
were
found doing well, entirely without, and the places where they should have been were indicated by the merest suggestion. Some specimens have
and these
will
the left tentacles
having been isolated and mated, all the young proved normal. None has been
abundant evidence that the red
With further material
and some have been discov-
able
colony was an old established one, and the snail had even acquired a local name. interesting
shells,
a scoop
left
in other directions, considerable in-
In the early
mal
ered with red bodies and white or nearly white shells. Most specimens over one year old are completely perforated in
be
if it
pleased to say that in fish culture circles,
is
Several specimens have been found with nearly white bodies and nor-
ce ntre
judgment of fishes, and if after a trial, it may be found to improve the I am flavor of fishes as food for man.
terest
light.
far greater
to the
and
to
many
features have been brought
bifurcated,
found with a single tentacle. The mating of the red form with the normal always produces dark offspring, and if two of these dark ones are mated.