: Argillaceous G'enus. 99 



III. VARIETY. 



Micaceous Sand-ftones. 



IY. VARIETY. 

 Micaceous Horn-ftone. 



Green hornftone mixed with mica. Gron- 

 ftein of Cronfted, 267, frequently contains 

 pyrites, and 20 per cent, of iron. 



V. VARIETY. 



Shiftus and Argillaceous Grit mixed in various 

 Proportions. 



VI. VARIETY. 



Shiftus and Hornftone mixed in various Pro- 

 portions* 



SPECIES II. 



Compounds of the Argillaceous and Calcareous 

 Genus. . 



I. VARIETY. 

 Bituminous Shiftus mixed 'with Limeftonc* 



Marmore Nero Antko. 



100 parts of this contain 18 of mild calca- 

 reous Earth, the remainder ihiftus, from 

 H 2 which 



