184 HOW HERMIT CRABS GET POSSESSION OF THEIR SHELLS. 
of the hermit crab in its younger stages. While the young 
hermit crab soon after leaving the egg is still provided with its 
powerful temporary swimming feet, and while the feet of the 
adult can only be traced as mere rudiments behind them, the 
whole test of the cephalo thorax and abdomen (which are sym- 
metrical) is of considerable consistency up to the last moults 
preceding the stage when it seeks a shell. At that time the 
young are no longer symmetrical ; the feet, which are now fully 
developed being largest on the right side, and the abdomen 
beginning to curve in the same direction away from the longi- 
tudinal axis. When the moult has taken place which brings 
them to the stage at which they need a shell, we find important 
changes in the two hind pairs of feet, now changed to shorter 
feet capable of propelling the crab in and out of the shell ; we 
find also that all the abdominal appendages except those of 
the last joint are lost, but the great distinction between this 
stage and the one preceding it is the curling of the abdomen : 
its rings, so distinctly marked in the previous stages, are quite 
indistinct, and the test covering it is reduced to a mere film, 
so that the whole abdomen becomes of course very sensitive. 
It is therefore natural that the young crab should seek some 
shelter for this exposed portion of his body, and, from what I 
have observed, any cavity will answer the purpose ; one of 
the young crabs having established himself most comfortably 
in the anterior part of the cast skin of a small isopod, which 
seemed to satisfy him as well as a shell, there being several 
empty shells at his disposal. This mechanical explanation still 
leaves unanswered the eagerness with which the crabs rushed 
for the shells, their careful examination of their openings, their 
taking the animal out and occupying its place ; all acts which 
seem to require considerable intelligence, and to show remark- 
able forethought. — Silliman’s American Journal, 
