102 THE HAUNTS OF LIFE 
ming larve, called zoex, marked by a spine 
rising vertically above the back, and by a tail 
sticking out at an angle to the rest of the body. 
These larve are swept out into the safety of 
the open water, and they swim about near the 
surface. They feed, they grow, they moult, 
and another form of larva results. This does 
the same, and a Megalops larva results, which 
is beginning to be like a crab. It has lost the 
spine; it has stalked eyes; it has got its full 
complement of legs. Now this Megalops 
bends its tail forwards and upwards under- 
neath the anterior part of the body (the 
cephalothorax) ; it ceases to be a free-swim- 
mer; it sinks to the floor of the sea, and creeps 
up the slope to its birthplace on the shore—a 
little crab about half the size of the nail of 
our little finger. 
There is an interesting illustration of ‘The 
Balance of Nature” in this connection. It 
seems that the shore-waters are, on the aver- 
age, richer in Plankton than any other waters, 
the reason being that they are always receiving 
abundant supplies of valuable salts brought 
down from inland by rivers and streams. So 
the shore-waters serve as a sort of nursery of 
minute creatures that get swept out to sea to 
