GASTEROPODS 371 
The littorinas fairly swarm in favorable localities upon all 
-shore stations. In Maine and Massachusetts the bold, rocky 
coast furnishes a home for several species. Often the rocks at 
low tide are black with them; the alge that cling in wet masses 
to the exposed rocks are alive with them. One cannot walk 
about in such localities without crushing hundreds of specimens. 
Sometimes they will be found clinging in clusters upon the piling 
of old wharves, or crawling about the bottom at or about the low- 
tide mark. The best specimens of Jvttorina are found in stations 
where they are bathed twice a day by pure, uncontaminated sea- 
water; those living near the mouths of streams, or where the 
water is brackish or impure, are usually small and degenerate. 
They are vegetable feeders, and have received the common name 
of “periwinkles.” In Great Britain they are used among the 
poorer classes for food. The animal has a short, broad muzzle, 
and eyes at the outer bases of the tentacles. The foot is longi- 
tudinally grooved, and there is a rudimentary siphonal fold in the 
mantle. The shells are turbinated, usually heavy, few-whorled, 
and with a round aperture. 
L. litorea. This is supposed to be an importation from the Old 
World—to have come over by way of Iceland and Greenland, and then 
to have migrated down the Labrador coast. For many 
years Cape Cod formed a barrier to its advance, but 
now the species is abundant at Newport, and is reported 
at New York. It occurs on the Maine coast in astonish- 
ing numbers, living in vast colonies on the rocks exposed 
at low tide. The shell is thick, imperforate (no umbil- 
icus), and usually has flat, spiral ribs. The columella is 
broad and white; the lip thin’and black. The general 
color varies from black to olive or to dingy gray—some- 
times reddish. The operculum is corneous, with the 
nucleus near the outer edge. Despite the variableness of this very 
common shell (the variations being chiefly in the height of the spire), 
it has certain unmistakable characteristics which, once seen, 
will enable the collector to determine it at once. 
L. rudis. A smaller species than the last. It is strong 
and coarse, with revolving grooves and ribs, or smooth, with 
interrupted whitish bands and spots. A very common vari- 
ety of this species is much smaller than the typical form, 
being about one sixth to one fourth of an inch long, smooth, 
with white and yellowish spots on olive. It clings to the rocks 
near high-tide mark, and is usually found attached to its 
resting-place by a bit of hardened mucus. While the typical L. rudis 
is heavy and banded,.with a moderately high spire and no color, this 
Littorina litorea. 
