416 BIBLIOGRAPHICAL AND CRITICAL NOTICE. 
That all the facts contained in it are reliable we have not the 
slightest doubt. Not only was Willis an exceedingly careful 
man, but he had the advantage of constant correspondence with 
Stimpson and Gould, Foreman and Binney, and these men deter- 
mined for him his doubtful species. They had themselves conf- 
dence in him, as shown by their frequent citations of facts on 
his authority, Stimpson especially, having quoted him frequently 
in his unpublished work on Northeast Amierican Molluses. 
Gould, in his splendid work on the Invertebrates of Mass. (2nd 
ed.) constantly quotes Willis, and Sir William Dawson does also 
in his works on the Post-Pleiocene Geology of Canada. We can 
have no better proof of the reliability of his work than is shown 
by the confidence reposed in him by his contemporaries. 
The value of his list must consist chiefly in the fact that it was 
the first detailed list of Nova Scotian Mollusca which gives exact 
localities, range, and relative abundance; and this means more 
than appears on the surface, for not only has it enabled Ameri- 
can naturalists to extend the range of species on our coast, and 
therfore has helped to wider and more accurate generalizations, 
but it preserves a record tolerably complete and accurate, as far 
as it goes, of distribution of forms at that period. The fauna of 
this region is not stable, but is constantly changing, and a cen- 
tury from now some of the forms will have a range very differ- 
ent from that described by Willis, and the Zoologists of that date 
will thank him for having preserved a precious record for them. 
He was the first man to point out the occurence of Southern 
forms upon our coast, in the Gulf of St. Lawrence, and on Sable 
Island, Jiving surrounded by cold-water forms, far north of their 
proper home, which is to the south of Cape Cod. Sir William 
Dawson had discovered these facts, it should be said, as soon as 
had Willis, or sooner, but Willis was the first to publish them, 
This subject has attracted the attention of later students, includ- 
ing Professor Verrill, Sir William Dawson, and the present writer, 
and all of them have found Willis’ discoveries, as embodied in his. 
list, of the highest value. 
(6). 1863. On the Occurrence of Littorina Littorea on the 
