PLATE XX. 



Zone of Aegoceras angulatum. 



Fig. 1. Aegoceras Charmassei, d'Orbigny. Side view, natural size: together with a 



very accurate tracing of the compli- 

 cated lobe-line, showing the lobes and 

 saddles in situ on the side of this 

 Ammonite. My collection from Lyme 

 Regis. 



2. — — Front view, showing sulcus on the 



siphonal area and rib tubercles there. 



3. — — — Back view of the same fossil. 



