Pvn H,i I'UitlS

240 lucinice.
and not less to the continual and successful labours of
Deshayes, Dunker, PfeifFer, Hanley, Reeve, H. & A.
Adams, Morch, Fischer, and other writers on the subject.
New forms are every day being brought to light, and re-
quire the former system of classification to be modified.
The old tree has put forth a greater number of new
shoots than the branches which have been severed from
it, and it is not less vigorous for the pruning ; even the
loppings, that have been planted and carefully tended,
are flourishing, and bid fair to rival their parent stem.
Species of Lucina abound in tropical seas, and Dr. Philip
Carpenter has enumerated no less than seventeen as
inhabiting the west coast of North America. Lamarck
asserted that in certain species the teeth become obli-
terated by age and disappear, which statement has been
repeated by subsequent writers. The British species
present no such anomaly ; on the contrary, their teeth
are developed in the course of growth, and become
stronger and more conspicuous
young.
in the adult than in the
1. Lucina spini'fera*, Montagu.
Venus spinifera, Mont. Test. Brit. p. 577, pi. 17. f. 1 . L. spinifera,
ii. p. 49, pi.
xxxv. f. 1.
Body clear white : foot very slender, and not swollen.
F. & H.
Shell obtusely triangular, with a somewhat oblique out-
line, compressed, solid and opaque, not glossy. Sculpture,
about 30 fine, plate-like concentric ridges, which are slightly
imbricated, their edges forming sharp spines on the dorsal
these ridges are more regular and equidistant in the
margin ;
young than at a later stage of growth ; between them are
extremely numerous and fine, but irregular concentric striae ;
and there are here and there a few longitudinal lines which
are not visible to the naked eye : colour pale yellowish-white :
epidermis fibrous and not very thin : margins slightly incurved
* Prickly.