411 



M. Walch observes, that it is very rare to find shells, or the re- 

 mains 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 

 adherered. 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 ap- 

 pears 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-STONA 

 ....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 'I our, in my hand, are among those wishes 

 which frequently arise, but which, hupe, reluctantly, refusing to 

 cherish, perish even, perhaps, the moment they are formed. liow 

 delighted should I be to view the wild Cambrian scenes, and to 

 trace the mountainous bottom of the antideluvian waters Nor 

 should 1 be less pleased at viewing the various specimens of 



* Recueil des Monumens des Catastrophes, &c, torn. iii. p. 30. 

 t Oryctogr. Helvet. p. 240. 



