184 



LYELL'S ELEMENTS OF GEOLOGY. 



Fossil Cephalopoda of Extinct Genera. 



Fig. 153. 



Ostrea vesicularis {OryphcBa glolosa, Sow.) 

 also in Upper Green-sand. 



FOSSIL CEPHALOPODA OF EXTINCT GENERA. 

 Cretaceous Period. 



Fig. 154. 



a. Turrilites costatus, Gault. 



h. Same, showing the indented border of the partition of the chambers. 



Portion of Baculites Faujasii, Portion of Baculites anceps. 



White Chalk and Upper Green -sand. White Chalk and Upper Green-sand. 



