Pvn H,i I'UitlS

NUCULA. 145
every coast from the Faroe Isles to Sicily and the
iEgean, and also
terranean.
the North African side of the Medi-
Mr. Clark says that the animal is timid, and therefore
difficult to observe. When in motion,
its foot becomes
a flat and nearly circular disk; its progress
is not
direct, but, turning round as on a pivot, its path describes
an irregular ellipse. M. Gay of Toulon informs
me that he constantly finds empty but perfect shells,
with the epidermis entire, inside starfishes, which would
therefore seem to have the power of killing the animal
and sucking it out of the shell, after swallowing it.
Petiver called this pretty kind the " silver cockle ?'} and
it is a favourite prize of children when they gather their
sea-side harvest in the autumn,
It may be
" On the beached margent of the sea."
"The shell from the bright golden sands of the ocean.
Which the emerald waves at your feet gladly threw,"
alluded to bv Keats in his delightful sonnet to some
ladies. Specimens are now and then found more convex
than others, even from the same localitv. Occasionallv
the lines of growth are raised ;
and where they cross the
longitudinal striae a decussated appearance is the result.
My first impression, that the N. radiata of Forbes
and Hanley was a distinct species, has yielded to a con-
trary conviction, in consequence of having compared
numerous specimens of all ages and sizes from various
places ; and I feel myself bound to reunite it with
N. nucleus. Typical, and even ordinary specimens of
each form cannot be confounded with each other ;
but
I have some from Plymouth and Tenby, which may be
referred to either form. The grounds of supposed dif-
ference are the comparative size, shape, convexity, and
H