940 Zs Littorina litorea Introduced or Indigenous? { November, 
specific identity under such conditions is altogether inconceiv- 
able. 
We have not been able to present any direct proof that L. Jito- 
rea did not exist in Nova Scotia before the present century. The 
testimony of the numerous lists (by independent observers, who 
could not have overlooked the shell had it been present) of shells 
on the coast of New England and New Brunswick in none of 
which occurs any mention of Z. /itorea, the testimony of its 
absence from the Post-pliocene deposits of other parts of Canada 
where L. palliata (along with which it always exists) has been 
found, the testimony of the Indian shell-heaps, into which it 
would certainly have been carried by the same means or for the 
same purpose as was Z. palliata, all of these combined afford 
almost absolute proof that the shell did not exist on the Atlantic 
coast of America outside of Nova Scotia. If these same tests 
could be applied directly to Nova Scotia the question would be 
settled as to whether it occurred there. An early list of the 
shells of that Province, or careful investigations into its Post-plio- 
cene deposits and Indian shell-heaps, would practically remove 
all doubt one way or the other. But the former does not exist 
and the latter has not been made. 
It must have existéd in Nova Scotia, if at all. But at the same 
time its absence from Greenland and Labrador, where, in accord- 
ance with what we know of the geographical distribution of ani- 
mals, it ought to occur along with Z. palliata if it is indigenous; 
the extreme improbability of its remaining in such a small area 
without spreading, with causes in existence tending to carry it 
from a less favorable to a more favorable habitat ; and the impos- 
sibility of the species remaining isolated from the parent stock in 
England for an indefinitely long time, and yet in spite of quite a 
‘differently conditioned habitat remaining specifically identical with 
it, all of these facts tend to show that it did not exist even i? 
Nova Scotia. Is not the conclusion warranted then, that ee 
rina litorea is not indigenous to America, but has been recently 
_and artificially introduced from Europe ? 
