PLATE LXXV. 



Zone of Lytoceras Jurense. 



Fig. 1. Harpoceras insigne, Schilbler. Abnormal young form, side view, natural 



size. My collection. 



2. — — — Front view of same fossil. 



3. — — — Abdominal view of do. 



4. Lytoceras hircinum, Schlotheim. Side view, natural size. School of Mines 



Museum. 



5. — — — Abdominal view of same. do. 



6. — — — Lateral view of another specimen, natural 



size. My collection. 



7. — — — do. variety do. do. 



8. Harpoceras Aalense, Zieten. Lateral view, showing entire side processes to 



the aperture. Prof. Waagen's collection. 



9. — — — Side view with prominent folds, natural size. 



My collection. 

 10. — — — do. do. Shell and position of suture line, 



natural size. 



