LUCINA. 85 
to show a minute terminal perforation. This metamorphosis 
is probably effected through its elasticity, and being distended 
with water. In the large specimen, of which this is the de- 
scription, the animal was more apathetic than the small one 
of the first part of these notes; the foot was never protruded, 
and of course no siphons, as none exist; the only movement 
for forty-eight hours was a central opening to admit the 
branchial water, and the exsertion of the margins of the 
mantle, which are quite plain. 
We have here the decided foot of the typical Lucine, 
agreeably to the descriptions of M. Poli and M. Valenciennes ; 
but if the latter is right as to there being but one branchial 
lamina‘on each side, in all the true Lucine, our present spe- 
cies, which beyond doubt has ¢wo on each side, would be an 
aberration from the typical Lucina, though so closely allied to 
it by the foot, which is of so singular configuration, that we 
think it a generic characteristic of far greater value than the 
single branchial plate on each side, which form prevails in all 
the Anatine, and in some of the Telline. We therefore 
would prefer to place this animal as a Lucina, even if it should 
turn out that all the Lucine have but one branchial lamina, 
which fact at present is by no means to be depended on; we 
consider the character of the tubular foot to be more worthy 
and important, in this case, than that of a singularity in the 
structure, or rather in the disposition, of the respiratory organ; 
and as to the branchial plate beimg a single one, it is more so 
im appearance than in reality, which is fully explained in the 
notes on Anatina phaseolina. In this very delicate animal 
we could not trace the connection of the foot with the viscera 
of the body, if it exists. M. Valenciennes says, that the water 
from the foot must enter and mix with the splanchnic con- 
tents ; we greatly doubt this fact, and refer for our reasons to 
the preliminary observations on the Lamellibranchiata. 
L. poreatts, Linneus. 
L. borealis, Brit. Moll. 11. p. 46, pl. 35. f. 5, and (animal) pl. M. f. 6. 
Exmouth, 2nd June, 1852. 
This day a live specimen, about ths of an inch diameter, 
