PLATE XIX. 



Zone of Aegoceras planorbis. 



Fig. 1. Aegoceras Belcheri, Simpson. Side view, natural size. From the cabinet of 



the Rev. T. Wiltshire, F.G.S. 



2. — — — Siphonal area of the same, smooth. 



3. — torus, crOrb. = Johnstoni, Soiv. Natural size. Prof. Deslong- 



champ's collection. 



4. — — — Siphonal area of same, smooth. 



5. — catenatum, Sowerhy. Side view, natural size. My collection. 



6. — — — Siphonal area, showing the ribbing. 



7. — — — Lobe-line, showing lobes and saddles magni- 



fied. 



8. Arietites scipionianus, d'Orb. Lateral view, natural size. My -collection. 



9. — — — Siphonal area showing deep keel. 



10. — — — Lobe-line with lobes and saddles magnified. 



