PLATE LXIV. 



Zone of Lytoceras Jurense. 



Fig. 1. Harpoceras radians, Schlotheim. Side view, natural size. My collec- 

 tion. 



2. — — Front view, do. 



3. — — Back view, do. 



4. — — — Lobe-line, magnified. 



5. — — Another specimen, side view, do. 



6. — — Front view, do. do. 



7. — — — Back view, do. do. 



