THE SCHOOL OF THE SHORE 51 
A common accident on the seashore is that 
a crab gets its leg badly broken by a moving 
stone. When that happens the crab goes in 
for surgery. By a very forcible contraction 
of the muscles at the base of the damaged leg 
the crab manages to break it off across a weak 
line. And just below this breaking line there 
is inside the base of the leg a two-flapped 
membrane which closes up the wound and 
prevents bleeding. Inside the bandage a new 
leg is formed in miniature, and at the next 
moult this shoots out like a Jack-in-the-box, 
and soon hardens. 
COLOUR CAMOUFLAGE 
The common shore-crab (Carcinus menas) 
occurs in many colours when it is young, and 
these sometimes harmonise exactly with the 
rock of the pool in which the particular crab 
lives. But there is no change of colour except 
after a moult. It is different with the Aesop 
Prawn (Hippolyte varians) which takes on 
the colour of its surroundings, both when 
young and when adult, and can change from 
one colour to another with ease. It has a large 
repertory—red, yellow, blue, orange, olive, 
