C ^55 ] 
XXVI. Remarks upon a petrified "Echinus of 
a fimgular kind^ Jhewn to the Royal Society^ 
April 24, T755) hy theReverend^ic^dcc^ 
Pococke, LL, D. Archdeacon of Dublin, 
and F. R. S. found on Bunnan’r-Zv^?:;^^/, in 
iJx Parifih of Bovingdon in HertfordOiire, 
which is a Clay^ and fiuppofed to have bee?i 
brought with the Chalky dug out of a Pit 
in the Field, By James Parfons, M. D, 
and F, R. S» 
>iy 9 > 175*5- 
Read April 17, H E round echmites are for the 
jL nioft part found in chalk-pits, and 
they are in general, when recent, the mod: tender 
in their (hells ; fo that the chalk is the moft favour- 
able bed for them to be preferved in long enough to 
be petrified ; whereas in other kinds of matter thefe 
would be mouldered and deflroyed before the pe- 
trification could commence ; and it is very fingular, 
that almoft all thofe in the chalk are filled with 
flint, or partly chalk and partly flint, and fome- 
times with cryfial. Now, as all flints and agates 
are nothing lefs than cryfial debafed by earth, 
and as it is in beds of chalk that thefe, as well ae 
multitudes of large ftones, are found, one would be 
almofl: induced to believe, that chalk degenerated 
X 2 int» 
