270 



OUR COMMON BRITISH FOSSILS. 



dead shell of an Ammonite, etc. where it settled, there 

 it grew, adapting its expanding shell to the object it 



Fig. 254. Ostrea vescicularis Fig. 255. Cardium Lil- Fig. 256. Exogyra. 

 (Chalk) lam tin (Greensand). conica (Greensand). 



was attached to ; and so in the Chalk-pits near Nor- 

 wich we find this very common fossil more than half 



Fig. 257- Pecten quadri- Fig. 258. Inoceramus 

 costatus. concentricus. 



encircling the solid shafts of Be- 

 lemnites, or actually taking the 

 impression of some coiled Am- 

 monite 



Other bivalve mollusca of the Chalk are the grace- 

 ful Inoceramus mytiloides and /. labiatus, the latter 

 not unfrequent near Dover, whilst the former is found 

 generally in the Lower White Chalk. 



^ a Parkinsonii. 



