THE SHELL-FISH OF THE COAST. 95 
covered by the sea. We find them clinging to rocks, 
to old wharf-piers and other immersed timber, to 
sea-weeds and the grass-culms of marshes, as well 
as enjoying the more placid retreats afforded by the 
sluggish waters of the tide-water marshes, pools, 
and ditches. The positions selected by them, usu- 
ally just within the reach of high-water, would 
seem to indicate a positive aversion on the part of 
the animal to the full waters of the sea, and they 
appear rarely to venture into the embrace of the 
surf. One species of our coast (Littorina rudis) has 
been known to live a week out of water, while an- 
other, from the West Indies, survived similar depri- 
vation for a full year; a species from the North 
European coast, again, has been found to bear with- 
out apparent discomfort a submersion of eighteen 
hours in fresh water. 
The largest species of the New Jersey coast is 
the big brown periwinkle (Littorina irrorata), which 
not infrequently measures upwards of an inch in 
length. It is readily distinguished by its robust, 
deeply-colored shell, which shows numerous prom- 
inent revolving lines on its surface. A much smaller 
form is the somewhat flattened and obtuse Littorina 
palliata (P1.1, Fig. 23), whose yellowish color, more 
or less speckled with brown, serves to distinguish it. 
It does not appear that the periwinkle is anywhere 
extensively used for food on the American coast, 
although prodigious quantities are periodically 
brought to and sent from the British markets. It 
is estimated that about the year 1865 the English 
periwinkle-supply amounted to not less than 2000 
B 3 
