$. III. DIST. CHAR. Soil. 175 



Argillite, in strata. Common. 



Rubblestone, in strata. Rare. 



Basalt, trap,, wacken, and greenstone, in strata and 

 -veins. Very rare. 



Sandstones,, in strata. Very common. 



Sand and gravel, in strata sometimes the seat of 

 woodstone. 



Jasper, in strata and masses. Very rare. 



Porphyry, in strata. Very rare. ( v. Kirw. G. Ess. 

 p. 2*7.) 



Hornstone or chert, in strata and masses. Com- 

 mon. 



The Saline ( sedes salina ) consists of 



Common, or rock salt. Very rare. 



The Metallic (sedes metallica) consists of 



Argillaceous ironstone, in strata. Very 'common. 



Bog ironstone, in masses. The sest of petrified 

 wood sometimes. 



Magnetic ironstone, in veins. Rare. 



Iron pyrites, in strata and veins. Rare. 



The Inflammable (sedes inflammabiHs) con- 

 sists of 



Pitcoal, and its varieties, in strata. Common. 



Peat. Common. 



C. 155. THE MATRIX (Matrix) is the 



body of mineral matter immediately adherent to, 



and generally surrounding, the extraneous fossil. 



This is sometimes merely a part of the seat (152) 



but is, also, frequently a distinct formation. 



