140 . III. DIST. CHAR. Substance. 



both the matrix and substance of shells and 

 other marine bodies. They are from Bake- 

 well, Derbyshire f. 

 Liihomarga. 



Indurated. Kirw. p. 188. An earth, which ap- 

 parently belonged to this species, we once 

 observed in the form of fluviatile shells. 

 Clay. 



Potters'. Kirw. p. 180. Sometimes forms the 



nuclei in testal remains. 



Indurated. Kirw. p. 181. F. Veg. frequently 

 the substance of vegetal petrifactions. 



** Schists. 

 Shale. 



Common. Slate Clay. Kirw. p. 182. F. Veg. 



very common. 



Bituminous. Kirw. p. 183. F. Veg. some- 

 times An. 

 Slate. 



Argillite. Kirw. p. 234. Clay Slate. Jam. p. 

 334. F. Veg. and An. Argillite, when not 



t The Rottenstonc of Derbyshire is evidently produced by the 

 disintegration of our black limestone or marble, above which it is 

 deposited not over coal, as Graelin, we know not from what au- 

 thority, has asserted. In other countries, Tripoli originates, pro- 

 bably, from the decomposition of argillaceous stones, as the author 

 just mentioned observes, that his Argilla Tripolitana (which he 

 considers as a species distinct from the Derbyshire rottenstone) is 

 frequently decorated with vegetal impressions, 



