44 
BULLETIN OF THE NATURAL HISTORY SOCIETY. 
coast of New England prior to 1868, but has since spread 
southward very rapidly, reaching Casco Bay about 1873, Cape 
Cod in 1875, New Haven, Conn., in 1879. The evidence- 
bearing upon the question of whether or not it is introduced, 
would be out of place here. It will be found in the work by 
the author, cited below]. 
Habits. It is not difficult to distingulisli this shell from our other 
littoral rock-loving Gasteropods. Our native Periwinkle, L. palliatav 
resembles it most closely; but that is much smaller, much thinner and 
lighter and entirely lacks any of the revolving raised lines so well 
marked iu L. litorea. This latter character marks it 
off well from young specimens of Lunatia Jieros. 
From L. rudis it is separated by its greater size and, 
the greater number and less prominence of its re- 
volving lines and by the shape of its mouth or 
aperture; in L rudis the latter is nearly round, in L. 
litorea it is pear-shaped. From Purpura lapillus and 
Fig. 9. — Littorina Buccinum undatum it is readily distinguished by the 
Litorea. Natural absence of a posterior prolongation of the shell into 
Size. a canal. Large specimens are over an inch in length, 
but ihe average size is a little below this. 
The Periwinkle lives on the rocks between tides. It is a vegetable 
eater, and uses its long file-like tongue or lingual ribbon, which its 
relatives employ to bore through the shells of other Molluscs, for rasp- 
ing up minute sea weeds from the rocks. It really grazes on these sub- 
marine pastures as do cattle on land. This mode of taking its food 
results in direct value toman, for in England Oyster cultivators distribute 
them over the beds to keep the Oysters free from seaweed. It has not 
been observed to attack other Molluscs. From its living on rocks 
between tides and possessing considerable vitality, it is liable to be taken 
on ships with ballast, and it was probably in this way that it was intro- 
duced into America from Europe. 
Economics. This is one of the best of our Food-molluscs, 
a fact proven by the quantities sold both in foreign markets 
and our own. It is not used as yet to any extent in the 
United States, probably because it is of so recent introduction 
and because of its scarcity in the vicinity of the markets of 
New York — the great mollusc-market of the Eastern United 
States. In England there are no exact statistics to show the 
extent of its use, but it is estimated that in London alone- 
more than twenty-five hundred tons, worth fifteen thousand 
