Two or three specimens of another curious crab are also in our haul.
Unlike the _Gonoplax_, the little Nut-crab[116] is not by any means
conspicuous in a chaotic heap like this; it requires a sharp eye, and
one familiar with the form, to discern him. Remarkably sluggish, he
remains motionless; his tiny limbs are almost concealed under the edges
of his shell; his body is destitute of sharp angles; its colour is a
dull white: in fact the eye might roam over it a dozen times without
supposing it anything more than an irregular rubbed quartz pebble.
Yet when you pick it up, it is a pretty little Crab. The form of the
body is unlike that of any other of our genera; indeed the type of
which it is a representative, though largely developed in the tropical
and sub-tropical seas, scarcely reaches to our shores. Some of the
allied species in the hotter parts of the globe, are very curious, such
as the _Calappa_, a crab in which the very short limbs are so closely
packed to the body, and so wholly concealed by the smooth and rounded
shell, that the curious sailor often picks it up and pockets it, as
a pretty white stone, little suspecting that he has a living Crab in
his fob. And there it lies for hours, perhaps, till he pulls out his
supposed pebble, which has not ventured all the while to attempt to
crawl.
I believe almost all we yet know of the habits of the timid little
Nut-crabs is derived from the portrait that I drew of one of them[117]
some years ago, from specimens that I obtained at Weymouth. Since then
I have repeatedly kept it in captivity for long periods at a time, and
indeed I have one or two now. Yet I have little to add to the sketch I
then drew of its manners. It is inert, folding its tiny legs on itself
when touched, and remaining motionless for some time. It buries itself
in the gravel, descending backwards: this is a somewhat slow process,
suited to its usual phlegmatic habit. It brings its hindmost pairs of
feet on each side together; then thrusting down their united points,
opens and expands them, forcing apart the gravel; at the same moment
the posterior part of the body is brought down into the hollow thus
made, and the action of the feet is repeated. The process is continued
until the hinder parts are covered and the muzzle alone is visible,
with the two claws. Thus it sits quite still, reminding one of a toad,
the broad triangular pedipalps that fit so close occasionally opening,
like the folding-doors of a tiny cabinet, and allowing the palpi to be
thrust out to wipe the minute eyes. The face, when examined with a lens
through the glass walls of the aquarium, has a most funny expression,
being singularly like that of an ancient man.
Like many marine animals, _Ebalia_ uses the hours of the night as its
chief season of activity. As long as the candles are in the room, it
remains pretty still, but as soon as darkness reigns, it sets out on
its travels. Not indeed with the railway pace of some of its fellows
does our little ancient travel; he is but a “slow coach;” but he gropes
about among the pebbles, and is usually found the next morning, buried
at some distance from the point where the previous evening had left
him.[118]