PLATE XV. 



Zone of Aegoceras angulatum. 



Pig. 1. Aegoceras Liassicum, d'Orbigny. 



2. 

 3. 



4. 



5. 



6. 



7. 



8. 



9. 



10. 



11. 



12. 



Aegoceras intermedium, PortlocJc. 



Aegoceras Belcheri, Simpson. 



Aegoceras tortile, d' Orbigny. 



A fragment from the Trent Valley, 

 Lincolnshire. Rev. J. E. Cross, 

 P.G.S., Appleby, Brigg, Lincolnshire. 

 Side view of the same, natural size. 

 Side view, natural size. Museum of the 

 Irish Geological Survey. One of 

 General Portlock's type specimens. 

 Siphonal area of the same fossil. 

 Side view of a large specimen from the 



same collection. 

 Siphonal area of the same shell. 

 Side view, natural size. Lower Lias, Robin 

 Hood's Bay. Woodwardian Museum, 

 Cambridge. Leckenby collection. 

 Siphonal area of the same fossil. 

 Lobes and saddles of same highly magnified. 

 Side view, natural size. Sent me by Monsieur 

 A. Etallon. Collected in the Lower Lias, 

 Prance. 

 Siphonal area and dorsal lobes of same. 

 Front view of siphonal area. 



