n8 The S^tural Hiftory 
was informed by a perfonof good credit, of a Jlone of this na- 
ture refembling a Cockje-Jhell, found in the belly of a Beef^ where 
in all likelyhood it bred, and (liot into that figure : Which if true^ 
fays he, there can be no reafon to doubt, but that thofe in the 
Quarries and other places arefo generated. 
113. But againft this opinion there are feveral confjderable 
oh]e5iions brought by the ingenious Mr. HooK-, Steno and 
Boccone^ which I ffiall next faithfully propound to the beft ad- 
vantage, and then fee whether they may not more eafily be 
folved, than the arguments on the other lide perhaps are like 
to be. 
114. Firft, That amongft thofe ftones^ there are fome with 
theperfed fiell^ in figure, colour and fubftance, fticking to their 
furface; efpecially, fays Mr. //oo^*, (difcourfing of thefe mat- 
ters} thofe Serpentine or Helical ftones were covered with^ or re- 
tained the pAning or f earl-colour' d fubfiance of the infide of a^\\t\\ , 
vphich fuh fiance onfiome -parts of them w 06 exceeding thin ^ and might 
he eafily rubb'd off\ on other parts it vpos pretty thicks, and retained a 
white coat^ or flaky fubftance on the top^ juft like the out fides of fiuch 
fliells ; fome of them had very large pieces of tbe fliell, very plainly 
fticking on to them^ which were eafily broken or faked off by degrees. 
Add hereunto fome particulars mention'd by i. That 
there was found a Fearl-bearingjhell in Tufcany, a f earl yet fiickjng 
tothe^itW. 2* A piece of the great SiidL-mcic [^\nn^m?inn^^^ in 
which the filk-Uke fubftance within the fhell being confumed^ the co" 
lour of that fubftance did remain in the earthy matter which had fiU 
led the (liell. 3. That about the City of Nohitm^ there are many 
beds of earthy not flony^which do abound with true Cockle-fliells, that 
havefuffefd no change at all, and yet they muft needs have lain there 
above '^cooyears ; whence it ps evident^ thattbat part of Tufcany 
wa5 of old time covefdwith the Sea : And why then might not as 
well all thofe other places where thefe petrified Jhells arc found? 
4. To which alfo let me add, that at fome places herein Eng-* 
land, ^2iYUcVi\zi\y 2il Cats-grove nt-^v Reading, a place fufficiently 
remote from the Sea (of which more at large whenl come into 
Berkrfiire') they meet with a bed of Oyfter-fiells both flat and gib- 
bous, about 1 2 or 14 foot under ground, not at all/e/n)?e^/, all 
of them opened, except fome very few, that I fuppofe haveca- 
Micrograph. Objcrv, 17. V In Fredroma- 
fually 
