Companions of the Flat-crabs, closely allied to them in all essentials
of form and structure, yet widely separated by general figure and
appearance, and to some extent by habits too, are the Squat-lobsters.
They, too, are somewhat flat, but they are more decidedly lobster-like,
with a distinctly jointed abdomen as broad as the body, terminating
in wide and strong swimming-plates. This portion is, during rest,
thrown-in under the body, much more completely than a true lobster or
prawn can do it, and yet is by no means so permanently set in that
position as in the true crabs. The Flat-crabs and the Squat-lobsters
constitute an intermediate group between the short-tailed and the
long-tailed Crustacea, the Flat-crabs inclining to the one, the Squats
to the other alliance. When the abdomen is wrapped-in, the outline of
the Squat is nearly oval, particularly in the commonest species, the
Olive or Scaly Squat.[94] That of the Scarlet or Embleton’s species[95]
is a longer ellipse. The front runs out into several sharp spines,
as do also the edges of the carapace; and the inner edges of the
front limbs, which carry long and stout claws, are very spiny. More
formidably armed in this respect, however, than either, is another
species, found occasionally at low-water, the Painted or Spinous
Squat,[96] all the limbs being set, on both edges, with stout sharp
prickles. The last named is the largest kind, being sometimes four
inches long; then the Olive, which is commonly from two to two and a
half; while the Scarlet rarely exceeds an inch and a half. They differ
very much in colour, the Olive being of a dull blackish green, with
narrow transverse lines of pale yellowish; the Painted somewhat of the
same general hue, but with the eyes and the tips of the claws of the
most vivid scarlet, while the body is varied with lines and spots of
an equally brilliant azure. Embleton’s is of a more or less bright
red, varying from a light orange or warm cream colour to a full orange,
clouded with patches of deep scarlet. The last is an inhabitant of deep
water, obtained only by the dredge; by this means, however, I obtain it
in considerable numbers. The other two are found, the first abundantly,
the second rather rarely, under stones in our coves. I have found, in
autumn, in such situations, several specimens of small size, rather
smaller than full-grown Embletons, which I conclude to be the young
of the Painted. The whole body is pale blue, tesselated all over with
black and reddish brown; the legs are banded with red, and the hands
are of the same colour. They have a very pretty appearance.
The whole race are very cautious and timid. With the long claws,
and the longer antennæ, stretched out to their utmost in front, the
suspicious Squat feels the unknown ground with delicate touches; should
he touch any object that moves, he gives on the instant a vigorous flap
with the broad incurved tail, and shoots backward through the water to
the distance of several inches. At the same moment all the legs are
thrown forward in the line of the body, to diminish the resistance.
Mr. Couch says: “It is very remarkable to witness the accuracy with
which they” [he is speaking of the Painted species specially] “will
dart backward _for several feet_ into a hole very little larger than
themselves: this I have often seen them do, and always with precision.”
This would surely be a remarkable feat for an animal in the air; how
much more through a medium so dense and resisting as sea-water!
I have elsewhere[97] described and figured the young of a species of
this genus in two of its stages. In the first it may be compared with a
prawn, having a lengthened slender body, whose fore part is protected
by a prawn-like transparent carapace, with an immensely long straight
spine in front, and two hooked ones behind. In the next stage the
general figure is acquired, but still the form is more like that of
_Porcellana_ than of _Galathea_.