Pvn H,i I'UitlS

OSTREA. 43
aeration from the atmosphere. The green colour, so
much prized by the Parisians, is owing to the oyster
feeding on the Navicula, a kind of Diatom or vegetable
organism which abounds in comparatively
brackish waters. According to physiologists the intestine
passes the heart without coming into contact
rule with
with it, being an exception to the general
respect to the relative position of these organs
still and
in the
Acephala. The oyster, therefore, cannot in fairness be
twitted with the proverb that the way to the heart is
through the stomach. Nor is the idea of its being
( f crossed in love }> less fallacious, seeing that each in-
dividual is of both sexes and can only be enamoured of
itself. Clark, as well as Gr. B. Sower by,
asserts that the
animal has two adductor muscles, and that the corre-
sponding impressions may be seen in each valve, the
posterior one being very small and placed close to the
hinge. I have not been able, however, to detect more
than one impression, which lies nearly in the middle.
I would therefore invite the attention of naturalists to
On it depends the
the elucidation of this simple point.
Lamarckian division of the Lamellibranchiata into
Monomyaria and Dimyaria, the oyster being the type of
the former group. Dr. Fischer says that the adductor
muscle in Pecten (which is allied to the oyster and
belongs to the same group) is divided, so as to form an-
terior and posterior bundles placed at different angles'
He is of opinion that the group of Monomyaria exists
only in appearance and not in reality. The cartilage
and ligament advance with the growth of the animal, in
consequence of which the old layers become useless and
are external. The oldest or first-formed portions of the
shell cease in time to be occupied by the animal, so that
the beaks become disunited and in adult specimens are