PLATE LII. 



Zone of Aegoceras Jamesoni. 



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



2. — Siphonal 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. 



