411 
M. Walch observes, that it is very rare to find shells, or the 
remains of any marine animals, among mineralized wood. He 
knows, he says, of very few instances indeed^. Scheuchzer describes 
a specimen of fossil wood, to which is also affixed a fossil oyster f. 
Davila also describes a piece of fossil wood to which an ammonite 
adhered. I have in my possession a very beautiful specimen of fossil 
wood, imbedded in a piece of the rock from Charmouth, in which is 
also fixed a very perfect spathose ammonite, and other specimens in 
which ostracitce are thus attached. But the fact appears to be really 
this, that this junction of animal with vegetable substances, in a fossil 
state, is only rare in those fossils which are actually silicious. 
Yours, &c. 
LETTER XLIII. 
SECONDARY VEGETABLE FOSSILS IN SCHISTI IN SAND-STONE 
IN CALCAREOUS STRATA IN ARGILLACEOUS NODULES. 
It gives me much pleasure to learn, that you purpose to extend 
your tour into Wales. The visiting of Dorsetshire, Devonshire, 
Somersetshire, and Gloucestershire, those vast mines of secondary 
fossils, and the traversing of Wales, with that pleasing and instruc- 
tive companion, Aikin’s Tour, in my hand, are among those wishes 
which frequently arise, but which hope, reluctantly refusing to 
cherish, perish even, perhaps, the moment they are formed. How 
delighted should I be to view the wild Cambrian scenes, and to trace 
the mountainous bottom of the antediluvian waters ! Nor should 
I be less pleased at viewing the various specimens of coal-slates, 
* Recueil des Monumens des Catastrophes, &c. tom. iii. p. 30. 
■|- Oryctogr. Helvet. p. 240. 
