118 
ANIMAL CURIOSITIES 
the shells of living bivalves such as cockles 
and mussels. One species is found in con¬ 
siderable numbers off the Irish coa’st. Indeed, 
so plentiful is it in certain districts that one 
writer reports that in nine out of every ten 
cockles he opened a pea-crab was present 
inside the shell. It is further recorded that 
in some instances two or three of the crusta¬ 
ceans may be found in a solitary bivalve. 
Then we have the masked crabs, so called 
because the upper portion of their shells is 
convoluted in such a manner that a rough, 
but nevertheless distinct, image of an uncouth 
human face is produced. One species known 
as the long-armed masked crab is found on 
our shores. Its antennae, unlike those of the 
majority of crabs, are of exceptional length 
and furnished along their inner edges with 
a double row of stiff hairs which interlock in 
such a manner that when they are held 
close together a tube is formed through which 
the crab is able to obtain a constant supply 
of water while its body lies buried and con¬ 
cealed beneath the sand. 
Another crab found in British waters is 
called the squat-lobster. In spite of its name, 
however, it is not a lobster, although in many 
respects it resembles one of those crustaceans. 
It is quite small, only attaining to a length 
