38
THE SEAS
but
about and burrow by means of a “ foot ”—
a
muscular organ, usually wedge—shaped, which can be
_
‘
prbtruded from between the two halves of the shell and by
its‘sudden movements enables the animal to progress by a
'
series of 'jerks on or beneath the surface of the sand.
Amongst the commonest of these are the cockle (Cardium
Ï
edule), which lives near theSurface, several species of Venus,
one of the Clams, which have ridges round the sbmewhat
,
“.
globular shell the better to enable them to grip the sand,
'
and a number w-ithmore attened shells, such as Tellina,
-
'
Macoma, Gari and the beautiful, highly—polished Donax, all
of which live deeper down than the cockle.
The long razor—
,
_
shells (Solen) may occasionally be dug at low tide ; in it the
two halves of the shell form a —cylinder with the’two ends
open, the lower one enabling the foot, and the upper One the
two siphohs concerned with the circulation of water and the
supply of food, to be protruded.
'
Worms there are in plenty, usually with a delicate,
colomed ring of tentacles round the head end.— They live
:
buried with only these tentacles exposed for the capturé of
their ne food,withdr‘awingthem on theapproach of an enemy
.
or when the tide' retreats.
Of such are the Terebellids, to
be recognized by their sandy tubes the upper ends of which,
fringed with ne laments, project above the surface, also
Amphitrite (Plate 77), a ne red worm with a bush of
sinuous tentacles.
Other worms of a carnivorous habit,
such as Nephthys, are found, while, cOmrhonest of all, is the '
AreniCola, whose castings are so common dotted
over the sandy shore (Plate 18).
Likethe earth worm on
“land, it spends its timeswallowing thesand' in -which it
lives, passing it out in the form of the familiar castings.
'
The head of the animal lies at the bottom of a small depres'
sion and the mouth
in sand which, since
,
the burrow is usually U—shaped, is conveniently disposed oi
THE SEAS
but
about and burrow by means of a “ foot ”—
a
muscular organ, usually wedge—shaped, which can be
_
‘
prbtruded from between the two halves of the shell and by
its‘sudden movements enables the animal to progress by a
'
series of 'jerks on or beneath the surface of the sand.
Amongst the commonest of these are the cockle (Cardium
Ï
edule), which lives near theSurface, several species of Venus,
one of the Clams, which have ridges round the sbmewhat
,
“.
globular shell the better to enable them to grip the sand,
'
and a number w-ithmore attened shells, such as Tellina,
-
'
Macoma, Gari and the beautiful, highly—polished Donax, all
of which live deeper down than the cockle.
The long razor—
,
_
shells (Solen) may occasionally be dug at low tide ; in it the
two halves of the shell form a —cylinder with the’two ends
open, the lower one enabling the foot, and the upper One the
two siphohs concerned with the circulation of water and the
supply of food, to be protruded.
'
Worms there are in plenty, usually with a delicate,
colomed ring of tentacles round the head end.— They live
:
buried with only these tentacles exposed for the capturé of
their ne food,withdr‘awingthem on theapproach of an enemy
.
or when the tide' retreats.
Of such are the Terebellids, to
be recognized by their sandy tubes the upper ends of which,
fringed with ne laments, project above the surface, also
Amphitrite (Plate 77), a ne red worm with a bush of
sinuous tentacles.
Other worms of a carnivorous habit,
such as Nephthys, are found, while, cOmrhonest of all, is the '
AreniCola, whose castings are so common dotted
over the sandy shore (Plate 18).
Likethe earth worm on
“land, it spends its timeswallowing thesand' in -which it
lives, passing it out in the form of the familiar castings.
'
The head of the animal lies at the bottom of a small depres'
sion and the mouth
in sand which, since
,
the burrow is usually U—shaped, is conveniently disposed oi