LOWER MARINE FORMATION. 299 



Of these the chief is iron pyrites, which is frequently the 

 mineralizing matter both of the vegetable and animal re- 

 mains included in the blue clay. Selenite is also very 

 abundant ; and sulphat of iron sometimes effloresces, when 

 the clay is exposed to the air, from the decomposition of 

 the pyrites contained in it. .Phosphat of iron is also some- 

 times found; and it abounds in Epsom salt, and in fossil 

 organic remains. 



In some places, as at Bognor, it assumes a new charac- 

 ter; instead of a blue clay, we find a number of rocks 

 now appearing as detached masses in the sea, though 

 evidently forming portions of a stratum once continuous. 

 The lowest part of these rocks is a dark gray limestone, 

 or perhaps rather a sandstone, containing much calcari- 

 ous matter, enclosing many organic remains belonging 

 to the blue clay. The upper part is siliceous sandstone. 



This clay abounds in petrifactions, and of those the fol- 

 lowing copious list isgiveH in Mr. Webster's paper: 



Organic Remains in the Lower Marine Formation above the 

 Chalk in England. 



NAMES GIVEN BY LAMARCK- LINN^AN NAMES. 



Astroitae. Astroitas. 



Calyptrea trochiformis. Trochus apertus. Brander. 



Conus. Conus. 



Cyprea pediculus. Cyprea pediculus. 



Terebellum convolutum. Bulla sopita. Brander. 



OHva. Voluta. 



Voluta spinosa. Strombus spinosus. 



rnusicalis. luctator. 



bicorona. ambiguus. 



crenulata. Murex suspensus, 



