Journal of Proceedings. xciii
might remind the members that there was a recorded instance of a
caterpillar (the larva of Lithosia caniola) resembling a mollusc when
coiled up among its food plant. Of course the use of the resemblance
was obvious, as the rolled-up caterpillars had almost exactly the
appearance in form, colour, and size of the shells, and the difficulty of
finding them when thus feigning death was much increased. But in
the case before them, although he was not disposed to admit it as an
instance of protective resemblance, still it was possible to look upon the
superficial likeness of the shell to the bract as the raw material, so to
speak, upon which Nature might work to produce a more exact and pro-
tective resemblance, should a change of habit of the enemies of the
mollusc render such protection valuable.
Professor Boulger pointed out that several species of the Molluscan
genus Pupa quite as much resembled the Beech-bracts as the Clausiliae—
indeed he failed to recognize any close resemblance whatever in Mr.
Christy's examples. And to prove a case of protective resemblance we
ought to be able to show a gradation, whereas we have no fossil species
of Clausilia less like Beech-bracts than those exhibited.
Professor Boulger exhibited some large sections of woods, of German
manufacture, showing transverse, longitudinal, and radial sections of
the branch, designed for educational purposes. The specimens were
about forty in number, and included all the British species of forest trees.
Mr. R. M. Christy read the following short paper, and exhibited speci-
mens of the shells alluded to :—
Note on the White Varieties of Cochlicopa lubrica, C. tridens,
and Bulimus obscurus.
Of all the many striking variations to which animals and plants are
subject there are few of greater interest than those in which the usual
colouring-matter of the species has, for some reason or other, not been
supplied, leaving the individual pure white. This "Albinism," though
fairly common among animals, is, perhaps, still more often met with
among plants, but there is no branch of the animal kingdom in which it
is more often seen than in the Mollusca; in the terrestrial forms
especially a very large proportion of the species have varieties in which
the shell is more or less pure white. Without desiring to enter into any
general discussion on this subject (about which I am free to confess I
know very little), I wish to record a singular fact which has come under
my observation, and which I am totally unable to explain.
On the 26th of July, 1877, I was upon a certain ancient defensive
earthwork of considerable extent, within twenty miles of Chelmsford (it
is better, for obvious reasons, not to give the exact locality, but I shall
be happy to inform any conchologist in private), when my brother, who
was looking among the moss and roots of the grass for shells, discovered
a specimen of Cochlicopa lubrica, var. hyalina, and a further search
showed that this generally very scarce variety was far from rare there.
Since that time I have paid many visits to the spot, and have always
found the var. hyalina living in tolerable abundance, intermixed with the
type-form which is rather the more numerous. This species often lives
there among the moss and roots of the grass, but more often among the