[ 3 ZI ] 
It was found in Tool's Hole in ‘Derbyshire. Its 
Sutures or Diaphragms refemble thole of fome of 
the larger Cornua Ammonis ; but its Shape be (peaks 
it to be a Species of Nautilus ; and it is thought to 
be a Non ■ defer ipt, both in its natural and foffil 
State. 
VIII. 1 be Subjlance of a Letter from Mr. 
William Arderon F. R. S . to Mr. Henry 
Baker F.R.S. 
Read^ May I2 -/^\F all the feveral Kinds of Fifh 
17 4 8 ' which for fome Years pad I have 
been keeping in glafs Jars (in hopes of becoming 
acquainted with the Nature and Properties of thefe 
Animals, by having them daily under my Infpedion) 
none feems more impatient of Imprifonmcnr, if I 
may fo call it, than the Roach ; nor, if they are 
well look'd after, and fupplied often enough with 
frefh Water, have I obferved any, except the Roach, 
to become diftempered. But mod commonly, after 
this Fifh has been a little while confined, the finny 
Part of its Tail begins to drop off Piece by Piece 5 
and when the finny Part is all gone, a fort of Mortifi- 
cation feizes upon the Tail itfelf, and gradually creeps 
along until' it reaches the Intefiines, at which time 
the Fifh immediately dies. 
The Jaft Roach I had under this Diforder was 
about the Beginning of January when in the 
Space of a Month, it had loft the great eft Part of the 
Fin, which induced me to clip off the reft, hoping 
thereby 
