PLATE XXVI. 
Zone Arietites raricostatus. 
Fig. 1. Aegoceras biferum, Quenstedt. Side view, natural size. My collection. 
2. — — — Eront view, magnified twice. 
3. — — — Siphonal area do. 
4. — — — Side view, showing wing-like ribs, magnified. 
5. Arietites RARICOSTATUS, Small shell, natural size. My collection. 
6. — — — Siphonal view, magnified twice. 
7. — — — Front do. do. 
8. — — — Side view, natural size. My collection. 
9. 10. — — — Front and siphonal views of do. 
11. — — — Side view, natural size. My collection. 
12. — — - — Do. do. showing the distance 
of the septa from each other. My 
collection. 
13. — — — Front view of same shell. 
14. — — — Siphonal area of do. 
I 
