PLATE XV. 



Zone of Aegoceras angulatum. 



Fig. 1. Aegoceras Liassicum, cTOrhigny. 



A fragment from the Trent Valley, 

 Lincolnshire. Rev. J. E. Cross, 

 F.G.S., Appleby, Brigg, Lincolnshire. 



— — — Side view of the same, natural size. 

 Aegoceras intermedium, Portlock. 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. 

 Aegoceras Belch eri, Simpson. Side view, natural size. Lower Lias, Robin 



Hood's Bay. Woodwardian Museum, 

 Cambridge. Leckenby collection, 



8. — — — Siphonal area of the same fossil. 



9. — — — Lobes and saddles of same highly magnified. 

 10. Aegoceras tortile, d' Orbigny. Side view, natural size. Sent me by Monsieur 



% A. Etallon. Collected in the Lower Lias, 

 France. 

 Siphonal area and dorsal lobes of same. 

 Front view of siphonal area. 



4. 

 5. 



6. 



7. 



11. 

 12. 



