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Bulletin 35 
166 
Page j 8 
tiguous seas. To this number may be added 4 species, 
some of which j^robably exi.st elsewhere. .Yncula similis 
and Corbula pisiim are species of the European Eocene. 
I can detect no difference between the Matura examples 
and the English species, but some doubt of course rests 
on the determination, owing to the distance both of 
locality and of time. I think, from what has been 
stated, that we maN' consider it moderately safe to infer, 
that of the fossil mollusca of the Matura deposit there 
is a percentage of at least 10 extinct species. This 
would bring the deposit within the Pliocene period ac- 
cording to the classification of Lyell*, and in .searching 
for European equivalents, we should probabh’ find that 
the glacial deposits of Europe present the closest ana- 
logies with the Matura beds. 
I maj’ remark, b}" the waj’, that the fact has not 
practical!}’ been overlooked by Geologists that even 
where all the species are recent, 3’et if some of them 
are only found in distant seas and existing under dif- 
ferent climatal conditions to those obtaining in the 
localities where such species are found fo.ssil, the dif- 
ferences between the recent and fos.sil faumu mark a 
real progress in geological time, and entitle the strata 
from which the fossils are obtained to a distinctive name. 
The Matura deposits are however less remarkable in 
this respect than in regard to the .small size of the shells 
found in them, a point which will be dwelt upon in the 
following sections of this paper. 
3. — Conditions of Deposit. 
I shall now proceed to con.sider the conditions under 
which the present deposit was formed. It is probable 
from the sandy nature of the beds, that they were 
not thrown down at an}- very great distance from land ; 
w-hile it is evident that it could not have been in the 
form of a beach that the deposit was accumulated. 
The shells are many of them too fragile to have with- 
stood the attrition which accompanies exj)osure on a 
* Lyell, Manual of Elementary Geology, 5 ed. p. 105, and 
Supplement, p. 13. 
