PLATE XXII a. 



Zone of Amaltheus oxynotus. 



Fig. 1. Arietites impendens, Young 8f Bird. 



2. 

 3. 



4. 



5. 

 6. 



7. 

 8. 

 9. 



Collenottii, d' Orbiqny . 



Side view, natural size. Woodwardian 



Museum, Cambridge. 

 Front view of the same shell. 

 Siphonal area of do. do. 

 Young shell with sharp ribs and 



sulci. 

 The lobe-line magnified. 

 Side view, natural size. Woodwardian 



Museum, Cambridge. 

 Front view of same shell. 

 Siphonal area of do. do.- 

 The lobe-line, highly magnified. 



