122 TESTACELLA SCUTULUM, SOWERBY.
in it is made more pronounced, and the ribbon being tightened the
backwardly-pointing teeth on the outsides of the "spoon" stand up-
right, while the barbs of those on the opposite edges come nearer to
one another with an action resembling that of a steel trap. Should
an earthworm be near enough the barbs pierce and hold it, but the
victim got away in some cases where its end was not entrapped ;
otherwise the slug extends itself once more, enveloping the worm
completely, if its size allow. The general conclusions arrived at are,
that Testacella does not necessarily feed only at night: that it is
doubtful the slug stalks its prey at all, and that the strikingly rapid,
but more or less automatic, protrusion of the radula has given rise to
the fanciful stories of its crouching and springing. Again, the end of
the worm must as a rule be seized, for apart from other considera-
tions it is impossible for a large worm to be swallowed in any other
way, as two thicknesses would have to be taken in together. A way,
however, strikes one by which this last difficulty might be got over,
and this is hinted at by one of the authors quoted from in the paper,
namely, granting that a worm could be securely held by the middle
it might well get broken in half, and one portion becoming free the
other might be swallowed in the ordinary way; whether the second
half would afterwards be attacked is a question. The results are
summed up as follows :—
" It will be seen that Testacella is particularly well adapted for
catching its prey should it meet them in the mouth or other portions
of their tunnels. The slug on coming into contact with the head of
an advancing earthworm, appearing above ground, or what not, would
contract, and, shrinking back, would entirely block the way with
its now swollen body. The worm in endeavouring to proceed would
continue to irritate the surface of the slug, seeking the groove above
the slug's mouth—in some cases small worms actually managed to
force their prostomia into the oral aperture—and would be caught in
the grip of the radula as it was shot out, and held securely, the slug
maintaining, by its broadened body, a firm hold on the walls of the
burrow. This method of procedure would not, of course, prevent
the Testacella from attempting to secure worms in the open, its
stealthy movements not alarming the latter in any way, but it would
not be so certain of a meal, as the chances of a successful hit with
the radula are by no means so great."
The paper winds up with some remarks as to the specific dis-
tinctness of Testacella scutulum, Sow., which, apparently owing to the