XVI. 



FARINGDON SPONGE BED. 



425 



Amidst a multitude of sponges and shells which seem to have 

 been aggregated on the old sea-shore, like some beaches, or more 

 probably gathered in limited tracts of shallow sea, like ' sand- 

 banks ' in the German Ocean, many fossils are observed which 

 appear to have been drifted from older strata. This appearance 

 is not deceptive, for the mineral state and worn condition of these 

 fossils confirm the suspicions at first raised by their forms. Mr. 

 Sharpe c presents a list of twelve or more species, mostly from the 

 Kimmeridge clay and coral rag, which adjoin the deposit; very 

 few, if any, from the Portland rock, which in the course of its 

 denudation was probably carried southward during and previous 

 to the deposit of these beds. I have added a few species : 



Echinida 



Monomyaria 



Dimyaria 



Cidaria intermedia . 



florigemma . 

 Diadema depressum 

 Exogyra nana 



virgula 

 Ostrea deltoidea 

 Gryphsea dilatata . 

 Pecten vimineus 

 Perna mytiloides 



Myacites recurvus . 

 Belemnites Owenii, jun. . 

 explanatus, jun. 

 Ammonites several frag- 

 ments .... 

 Sphaerodus gigas 

 Ichthyosaurus 

 Plesiosaurus . 

 Teleosaurus 



Of the Coral rag. 

 Of the Coral rag. 

 Of the Coral rag. 



Of the Coral rag and Kimmeridge clay. 

 Of the Kimmeridge clay. 

 Of the Kimmeridge clay. 

 Of the Oxford clay. 

 Of the Coral rag. 



Of the Kimmeridge clay and the Port- 

 land rock. 



Of the Oxford clay or Kimmeridge clay. 

 Of the Oxford clay. 

 Of the Kimmeridge clay. 



Of the Oxford clay. 



Of the Kimmeridge clay. 



Teeth and vertebrae. 



Vertebra. 



Teeth. 



Further to the south, about Cole's Pits, Farnham, and Alfred's 

 Hill, sands prevail, and gravel-beds appear in limited spaces, always 

 resting on Kimmeridge clay, but fossils are rarely seen in any 

 of the exposures. 



Of other tracts containing small portions of lower greensand 

 in the vicinity of Faringdon, it is only necessary to say that they 

 conduct but a short way toward the chalk hills on the south, and 

 that no continuous band of these rocks occurs at the base of those 



c Geol. Journal, x. p. 182 (1853). 



