930 Js Littorina litorea Introduced or Indigenous? {November, 
lantic in such a way—they must have come, if they came by nat- 
ural means at all, by way of Iceland, Greenland and Labrador. 
This we find actually was the case with Z. palliata. Where it 
originated the writer does not know, nor does it matter in the 
present connection, but certain it is that it is now common to 
England, Greenland? Labrador? Acadia and New England. 
And not only does it exist in these places now, but it has fora ; 
long time past, for it is found fossil in Post-pliocene deposits in | 
England, in Southern Greenland? (Z. grénlandica = L. palliata) 
and in Canada, though not actually in Acadia. Dawson reports 
it from the Post-pliocene of Gaspé, and Lyell from Beauport* 
We may hence conclude that Z. palliata is, in the sense in 
which we have used the word, indigenous to America. 
But as to L. Zitorea, not only does the latest and best list of 
Greenland shells? make no mention of its occurrence there, nor 
does Packard in a list of the shells of Labrador’ (though he men- 
tions Z. palliata and L. rudis as “ abundant” and “not uncom 
mon”), but no trace of it has as yet been reported from any Post- 
pliocene deposits of Greenland, Labrador, Canada or New Eng- 
land. It is a shell much more likely to be preserved in such de- 
posits than LZ. palliata, being much larger and stouter—though 
neither, from their rock-loving nature, stand as much chance of 
being preserved as sand or mud-inhabiting species. All of these 
facts tend to show that Z. Ztorea was not introduced from one 
continent to the other either at the same time or by the same 
means as L. palliata, and that if by any unknown agency what- 
soever L. litorea had reached America, it must have been con- 
fied to Nova Scotia alone “until the middle of the Pee 
century. 
Bat we have another source of information about the shells 
which lived upon our coast before the advent of the Esr 
In the Indian shell-heaps along the coast of Maine and Ne j 
‘Brunswick, most of the edible mollusks of the coast are oe 
among the heaps of clam-shells. Dr. Wyman reports” that eae 
shell-heap at Crouch’s cove, Casco bay, Maine, Littorina pa 
_ l Forbes and Hanley’s British Mollusca, Vol. 111. 
? Manual and instructions for the Arctic expedition. London, 1876, 
: *Packard,.Mem. Bost. Nat. Hist. Soc., Vol. 1. 
Nat., I, 345. 
l NAT., Vol. 1, No. p1, 1868, 
