16 WEST AMERICAN SHELLS 
organ any one of us would find very embarrass- 
ing; but not so our happy clam, for never having 
possessed a head he feels no need of one. 
So he digs a burrow with his hatchet-shaped 
foot and pulls himself down into it and feels rea- 
sonably safe. To be sure he needs food and some 
kind of breath, but he is so wonderfully made 
that he has little trouble in obtaining either, for 
in fact they come together. He has two tubes, or 
siphons as they are called, which he pushes up 
through the burrow to the surface of the sand, and 
then opens them out in the clear water above. 
Then he starts his pump, which is a double-action 
affair, and the work begins. Water is sucked 
down one pipe and forced up the other, and with 
the water come particles of food and dissolved air 
for breath. His wonderful gills absorb the latter 
and gather up the former, which they pass on to 
the mouth that is waiting to receive the nourish- 
ment. 
When the tide goes out and the sand is left bare, 
our happy clam has just to wait, that is all. But 
if you walk along over his hole he may become 
startled by your footstep and suddenly pull down 
his siphons into his shell. As they are full of 
water, the result will be a little fountain which 
you will see spouting up for an instant and then 
disappearing. If you have a hoe or a shovel you 
may now dig the poor fellow out of his revealed 
burrow, and his fancied security will prove vain; 
but if he is a large clam his burrow may be too 
deep to be easily explored, and if he be lively 
he may dig too. 
