PLATE LII. 



Zone of Aegoceras Jamemni. 



Fig. 1. Aegoceras sagittarium, Blake. Side view, two thirds natural size. 



2. — — — Siphontil area of the shell, two thirds natural 



size. Collection of the Rev. J. E. Cross, 

 F.G.S. 



3. — '■ — — Lobe-line, magnified. 



4. — — — Side view of small shell, natural size. 



5. — — — Siphonal area of do. do. 



