Pvn H,i I'UitlS

LUCIN1D.E. 231
different genera have been described from various parts
of the world ;
and fossil species are still more abundant.
The " family likeness " is unmistakeable, and this
constitutes part of the value of the Luciniclce as a
natural group. After much consideration and study of
the question, and with great respect for the opinion of
the authors of the ' British Mollusca' and of M. Des-
hayes, I cannot agree with them that the long-established
genera of Loripes and Axinus ought to be
merged in Lucina. The great French conchologist has
lately made a strong protest against the dismemberment
of the last-mentioned genus; and he wishes it to be
retained, like the once glorious republic
of his own
country, " une et indivisible." To use his own words,
it forms " une grande unite." It may, however, be
questionable if the characters on which he lays so
much stress do not apply not only to the genus, but to
the family which has sprung from it, and whether there
are not other characters, although perhaps of inferior
value, that may serve to distinguish several genera. I
believe that such characters exist, and I will endeavour
to point them out in the proper place.
It can hardly
be disputed that each group of natural objects, whether
we call it a kingdom, class, order, family, genus, species,
or variety, has some peculiar feature of its own, although
we may not be able to detect it. The imperfection of
our knowledge has hitherto combined with the limited
capacity of our intellect in keeping us but partly en-
lightened ; and this must ever continue to be the case,
until the whole scheme of Nature, past and present, has
been unfolded to our view. Perhaps, even to the greatest
philosopher of modern days,
" Science appears but what in truth she is,
Not as our glory and our absolute boast,
But as a succedaneum, and a prop
To our infirmity."