PLATE 43. 
Fig. 1. 260. 13. Orthoceras 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. Orthoceras bilineatum. 
(Pag. 199.) 
2 a, b. Views of two individuals, showing the annulations and longitudinal striae. 
2 c. Transverse section of b. 2 d. Portion of the surface enlarged. 
Fig. 3. 262. 15. Orthoceras bilineatum, var . a. (Pag. 200.) 
3 a. A fragment of this variety. 3 b. Transverse section, slightly compressed, showing the siphon. 
3 c. An enlarged portion of the surface. 
3 d. A fragment denuded of the shell, showing the lines of septa which do not correspond to the annulations. 
Fig. 4. 263. 16. Orthoceras clathratum. (Pag- 201.) 
4 a. The fragment, natural size. 4 b. Magnified portion of the surface. 4 c. Transverse section. 
Fig. 5. 264. 17. Orthoceras vertebrale. (Pag. 201.) 
5 a. Ventral side of the fragment. 5 b Portion of the dorsal side. 5 c. Transverse section. 
Fig. 6. 265. 18. Orthoceras anellum. (Pag- 202.) 
6 a. A fragment of the septate portion of the shell. 6 b . Transverse section of the same. 
6 c. Enlarged portion, showing the striae, which, on a great part of the surface, are covered by a calcareous 
coating. 
0 d. A smaller fragment. 6 c. Transverse section. 6 f. Portion of the surface enlarged. 
Fig. 7. 266. 19. Orthoceras undulostriatum. (Pag- 202.) 
7 a. Ventral side of a fragment, showing the nearly transverse direction of the annulations. 
7 b. 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 f, 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. 
Orthoceras (O. trochleare ? )■ 
(Pag. 203.) 
