Pvn H,i I'UitlS

108 mytilid^e.
the glass. It is also curious to notice a young mussel
in a rock-pool, slowly and painfully warping itself along
by its extensile foot, the point of which is attached like
the sucker of a leech. The foot is stretched far beyond
the beak of the shell on the anterior side. For anato-
mical details of the animal I would refer my
readers to
tlfce admirable treatise of Professor Loven on the deve-
lopment of the Lamellibranchiate Acephala. The fry
has two very distinct eyes, which soon disappear and
are quite absent in the adult. The cilia which clothe
the gills are extremely beautiful and interesting objects
of microscopical examination. If a small portion of
one of the gills is cut off and put into sea-water, it will
swim about for a considerable time by means of these
cilia, appearing like an independent
animal. The shell
sometimes grows to a colossal size. In the '
tions '
Transac-
of the Imperial University of Moscow for 1863
is a notice by Dr. Nordmann of a gigantic form of the
present species found by Holmberg on Edgecombe Isle
in Russian North America. One specimen, which is
figured of the natural size, measures upAvards of 9
inches in length and 4^ in breadth, and is stated to
weigh 1 lb. 5 dr. 16 gr. The stunted variety (incurvata)
forms on some parts of our rocky coast a mass so closely
packed that the point of a knife could scarcely be thrust
between them. This was probably the " amazing bed
of small mussels " mentioned by Pennant in his '
Intro-
duction to Arctic Zoology/ and as to which he remarks,
11 1 think they were brought there by sea-fowl to eat at
leisure " ! Fabricius says it is viviparous, and that in
the spring he has found the fry lodged within the hinge
of their parent's shell ; but it seems more probable that
this was only a place of temporary shelter for them.
In the Shetland Isles the edible mussel is called "Crock-