t is otherwise. From the moment of its birth it is
called upon to enter life's battle alone; of brothers and sisters,
mother and father and home, it knows nothing. And such a tiny little
mite it is, too, needing a microscope to see it. Stranger still, at this
early period of life it is not the least bit like a crab; for a crab, as
most of us know it, is a creature with a shell broader than it is long,
and long legs, and a pair of pincers which can give a most painful nip
to unguarded fingers. As a youngster, however, he presents a very
different appearance, as may be seen in fig. 1. That is what he looks
like just after leaving the egg--a creature with a huge eye, a big round
body, and a long, slender tail--a sort of compromise between a crab and
a lobster, but without the familiar legs and pincers.

A little later he assumes a form which is certainly fantastic, for from
the top of the shell (as you will see in fig. 2) there grows out a long,
curved spine, while the legs have taken a shape suggesting jointed
paint-brushes. Later still the eyes grow out from the head and are
supported on short stalks, the legs and pincers appear, and lastly the
long tail curls up, till at last it grows into a curious three-cornered
shield and is carried tucked away under the body. As soon as this takes
place he becomes at once the crab with which we are familiar, and
changes no more except in size.

[Illustration: Fig. 3.--Last stage of Crab's Infancy: back view.]

[Illustration: Fig. 4.--Side view of Fig. 3.]

The strange flap hinged to the hinder edge of the body of the adult
crab, and held close to its under surface, really answers to the long
body of the lobster. To make this clear, look at the series of figures 3
to 6: fig. 3 shows the back view of the last stage of the crab's
infancy, and fig. 4 a side view of the same, where you will note that
the tail is already beginning to curl up. In fig. 5 you have the under
side of the full-grown crab with all that remains of the hinder part of
the body and the tail in the position in which it is carried during
life, and in fig. 6 the upper side with the tail showing as if it were
unfolded. If you compare figs. 5 and 6 with fig. 7 (a lobster), you can
see that the hinder part of the body of the crab, with the tail
unfolded, really does answer to that portion of the body of the lobster
which lies behind the last pair of legs.

[Illustration: Fig. 5.--Full-grown Crab, under side, showing t