THE LIFE OF THE SEA-SHORE. 147 
Galathea approaches the crabs more nearly than the true 
long-tailed forms. In the same pools, under stones or 
clinging to weed, you will find a near ally of Galathea—the 
minute porcelain crab, or crab-lobster. It is a little 
creature of crab-like. shape, with a tail much more 
sharply bent than that of Galathea. It uses its legs almost 
exclusively for locomotion; but if you keep specimens 
in confinement you will notice that occasionally, especially 
if attacked by other crustacea, it unfolds the tail and 
uses it aS a swimming organ. The strokes are feeble 
and slow, and do not carry it any considerable distance, 
but some trace of the swimming power still remains. 
Now all these belong to the highest group of crustacea, 
and of them there can be no doubt that the prawns and 
their allies are the most primitive. When the others 
forsook the deep water for the shore or the sea-floor 
they ceased to require the power of swimming, and the 
tail with its organs tended to be reduced. The lobster, 
Galathea, and the porcelain crab show successive stages 
in this reduction, and in the decrease of the swimming 
power. But this reduction may take place in two ways. 
The tail may be tucked in, as in crabs and porcelain crabs, 
or it may undergo reduction without becoming in-turned. 
This last is what has happened in the hermit crabs, who 
are forced to appropriate molluse shells to cover their 
soft defenceless tails. In them all power of swimming 
is of course lost, and locomotion is entirely dependent on 
the walking legs. The hermits, like the true crabs, can 
thus not escape their enemies by sudden swift movements, 
and to a greater extent even then the crabs have to depend 
_ upon passive means of resistance. In fact, when alarmed, 
they retract themselves suddenly into their burrowed 
house, and there wait till the danger passes by. The 
hermit crabs are interesting in many ways. They often 
form partnerships with other animals, such as worms and 
sea-anemones, with whom they live in mutual friendship, 
Most curious of all, perhaps, is their habit of perpetual 
flitting. Whether they change houses constantly, under 
natural conditions, I don’t know; but in confinement they 
are possessed of unlimited restlessness, and will go on 
