SIGNS ON THE BEACH 3 
causes, in the aggregate, considerable vibrations. Such sands 
are not uncommon, having been recorded in many places, and 
they exist probably in many others where they have escaped 
observation. They may be looked for above the water-line, 
where ‘the sand is dry and clean. 
We have to do, however, in this volume, not with the history 
of the past, nor with the action of physical forces, but with the 
life of the present, and to find this, in its abundance, one must 
go down near the margin of the water, where the sands are wet. 
There is no solitude here; the place is teeming with living things. 
As each wave retreats, little bubbles of air are plentiful in its 
wake. Underneath the sand, where each bubble rose, lives some 
creature, usually a mollusk, perhaps the razor-shell Solen ensis. 
By the jet of water which spurts out of the sand, the common 
clam Mya arenaria reveals the secret of its abiding-place. A 
curious groove or furrow here and there leads to a spot where 
Polynices heros has gone below; and the many shells scattered 
about, pierced with circular holes, tell how Polynices and Nassa 
made their breakfast and their dinner. Only the lifting of a 
shovelful of sand at the water’s edge is needed to disclose the 
populous community of mollusks, worms, and crustaceans living 
at our feet, just out of sight. 
Even the tracks and traces of these little beings are full of 
information. What may be read in the track of a bird on the 
sand is thus described by a noted ornithologist : 
Here are foot-notes again, this time of real steps from real 
feet. . . . The imprints are in two parallel lines, an inch or 
so apart; each impression is two or three inches in advance 
of the next one behind; none of them are in pairs, but each 
one of one line is opposite the middle of the interval between 
two of the other line; they are steps as regular as a man’s, 
only so small. Each mark is fan-shaped; it consists of three 
little lines less than an inch long, spreading apart at one ex- 
tremity, joined at the other. At the joined end, and also just 
in front of it, a flat depression of the sand is barely visible. 
Now following the track, we see it run straight a yard or 
