PLATE LIX. 



Zone of Harpoceras bifrons. 



^X.-LrtMD'S- 



Fig. 1. Harpoceras bifrons, Bruguiere. Side view, lobe-line aperture and lateral 



processes, natural size. My collection. 



2. — — Siphonal area with lobe-line do. do. 



3. — — Fragment of a small shell with groove. 



4. — — Do. do. do. 



