PLATE LXII. 



Zone of Harpoceras serpentinum. 



Fig. 1. Harpoceras exaratum, Young and Bird. Side view, natural size. My 



collection. 



2. — — Front view of do. do. 



3. — — Back view of do. do. 



4. — Lythense, — Side view, do. My 



collection. 



5. — Back view of same, do. 



6. — — Front view do. do. 



