Pvn H,i I'UitlS

246 LUCINID.E.
If Lucina has been properly made the type of a sepa-
rate family, and is no longer to be regarded as a genus
containing many sections or subgenera, the validity of
the present genus can hardly be questioned. A com-
parison of the characters above given
with those of
Lucina, as now sought to be restricted, will, I think,
suffice to convince most conchologists that Axinus is a
good genus. Those who are of opinion that the family
has no substantial or natural basis are of course at
liberty to adopt the old genus Lucina in its original in-
tegrity. I do not propose any new genus. Axinus has
already attained the respectable age of forty years.
is at present in some danger of being set aside as obso-
lete or unfashionable ;
but
Multa renascentur quae jam cedidere, cadentque
Quae nunc sunt in honore vocabula, si volet usus,
Queni penes arbitrium est et jus et norma loquendi.
These mollusks are of small size, and dwellers in mud
and sand at various depths of water. The species are
by
no means numerous. Three of them are British and
European,
and another is Cuban. Mr. Searles Wood
says, " Species strictly belonging to this genus
been described from any formation of an older date
It
have not
than the tertiaries : the shell called Axinus obscurus,
from the Magnesian limestone, belongs to a different
group, and has already been made a genus of by Pro-
fessor King, under the name of Schizodus." The shell
of Axinus has no tooth. What has been taken for such
is merely the point of the hinge-plate, near the beak,
which becomes thickened, and even projects a little, in
full-grown specimens. This process is unlike the tooth
of any bivalve. The connexion of the valves depends
wholly on the ligament, and is therefore slight. Sowerby,
in proposing the present genus, instanced A. anyulatus