tlie matter whereof they confift, and found in the midft 
of the Stone of ^Rocks and Quarries) as in rhofe that 
are not (b hard fuch as Chalk, Clay, and the hke : 
And this in the moft nnidland Countries as well as in thofe 
which are nearer to the Sea. He obferves, that thefe 
Shells are thus found inclofed in this Terreftrial Matter 
from the Surface of the Earth down to the very bottom 
of the deepett Quarries and Mines': That they lye ac- 
cording to the order of their Specifick Gravity, the hea- 
vier kinds deeper, the lighter nearer unto the furface of 
the Earth, and both the one and the other amongft Ter- 
reftrial matter, that is of the fame Specifick Gravity 
that they are of: And this not only in Englandy but in 
other parts of Europe y yea, in Afia^ Africa^ and America ; 
or in fhort, all the World over. But becaufe many 
Learned Men of late have doubted whether thefe were 
truly Shells or not, he removes that Doubt, and anfwers 
their Objedions, proving thefe to be the real Shells of 
once living Shefl-Filb, and that they were Originally 
generated in the Sea. 
This difpatch'd, he proceeds to thj^Body of the Work, 
which he hath divided into fix Parts. In the firft of 
which he examines the ways whereby other Authors 
have thought thefe Shells were brought to Land ; and 
particulaFfy thofe who fuppofe that there happen great 
Changes of Sea and Land : e, gr. That there have been 
many and great Iflands raifed from the bottom of the 
Sea by Eartljquakes ^ fuch as Rhodes and others : That 
the Center of Gravity in the Terraqueous Globe fliifrs 
and moves, and confequently the Water of the Sea moves 
alfo,- fo that it deferts thofe Trafts of Land which it 
formerly covered, and betakes it felf to others, which 
were till then dry Land. That the mud which is car- 
ried down into the Sea by Rivers, and precipitated at 
their Oflia, makes daily additions to the Earth, which 
therefore encroaches and gains upon the Sea, as the Sea 
in 
