Pvn H,i I'UitlS

TAPES. 361
fauna ; but it is universally common southwards as far
as the iEgean and probably Senegal.
The shell was well figured by Lister as English.
He
noticed the purplish-violet stain inside, and inquired
whether the dye of the ancients could have been procured
from bivalves as well as from univalves. This
question has never been answered by any physiologist
or antiquary. He also mentions that the shells are
called " purrs n in some parts of England ; Petiver and
Dale give the same provincial name. According to
Collard des Cherres, the Breton designation is " palourde/'
which is also applied in that province to Pec-
ten maximus. M. Gay informs us that it is known at
Toulon as " clouvisso." The animal makes a favourite
dish in continental seaports ; and Mr. Dennis writes
me word that both this and T. pullastra are eaten in
Sussex. It has been observed bv Mr. Rich to be more
tenacious of life than T. pullastra. He kept some of
the present species alive in fresh water for eight or nine
days, but none of T. pullastra survived for half that
time. He also found the colour of the shells of both
these species, when put into hot water or near a fire, to
change from dark purplish- brown to a brick-red hue.
Montagu justly remarked that the siphons differ from
those of T. pullastra in being divided to their origin ;
but he was mistaken in supposing that both tubes were
protruded in search of food. Mr. Clark says, "This
species is much more common than the P. pullastra ;
they live together in the same shingles, and have precisely
the same habitudes; notwithstanding this com-
munity they are very distinct." His opinion
on the
last point is the more valuable because he was by no
means a species-maker.
The young of T. decussatus are
nearly square, while those of T. pullastra are oblong.
R