PLATE 43. 



Fig. 1. 260. 13. Obthoceras textile. (Pag. 199.) 



1 a. A fragment of the natural size. 1 b. A portion of the surface enlarged, to show the striae. 



Fig. 2. 261. 14. Orteocbras bilineatum. (P^g' 199.) 



3 a, b. Views of two individuals, showing the annulations and longitudinal striae. 



2 e. Transverse section of 4. 2 d. Portion of the surface enlarged. 



« 



Fig. 3. 262. 15. Orthoceeas bilineatum, var. a. (Pag- 200.) 



3 o. A fragment of this variety. 3 6. Transverse section, slightly compressed, showing the siphon. 

 3 c. An enlarged portion of the surface. 



3 <i. A fragment denuded of the shell, showing the lines of septa which do not correspond to the annulations. 



Fig. 4. 263. 16. Oethoceras clatheatum. (Pag- 201.) 



4 a. The fragment, natural size. 4 b. Magnified portion of the surface. 4 c. Transverse section. 



Fig. 6. 264. 17. Oethoceras vertebralk. (Pag. 201.) 



."i a. Ventral side of the fragment. 5 i. Portion of the dorsal side. 5 c. Transverse section. 



Fig. 6. 266. 18. Oethoceras anellum. (Pag. 202.) 



6 o. A fragment of the septate portion of the shelL 6 6. Transverse section of the same. 



6 c. Enlarged portion, showing the stris, which, on a great part of the surface, are covered by a calcareous 



coating. 

 d. A smaller fragment. 6 e. Transverse section. 6/. Portion of the surface enlarged. 



Fig. 7. 266. 19. Oethoceras undulostriatum. (Pag. 202.) 



7 a. Ventral side of a fragment, showing the nearly transverse direction of the annulations. 



7 4. Dorsal side of the same, the specimen cylindrical. 7 c. Transverse section of the same. 



7 d, e. Two smaller fragments of the species, compressed in different degrees. 

 7/, g. Transverse sections of the two last. 7 h. An enlarged portion of the surface. 



7 i, k. Another fragment and section, showing the position of the siphuncle. 



Fig. 8. 267. 20. Oethoceras (O. trochlearet). (Pag. 203.) 



