EXPLANATION OF THE PLATES. 



Plate VIIL 



Fig. 1. Belemnites longissiraus : p. 60. 



Fi"-. 2. Transverse section of the guard of the same : p. 60. 



Fig. 3. Belemnites sulcatus : see p. 59. 



Fig. 4. Transverse section of its guard, showing in the centre its nearly circular out- 

 line : p. 59. 



Fig. 5. A variety of Belemnites sulcatus, showing the abbreviated laminae as they 

 form the longitudinal groove : p. 59. 



Fig. 6. Belemnites aduncatus : p. 59. 



Fig. 7. The apex of the same : p. 59. 



Fig. 8. Transverse section of the guard : p 59. 



Fig. 9. Belemnites acutus : p. 60. 



Figs. 10 & 11. Belemnites tripartitus ; — a front and back view : p. 60. 



Fig. 12. Transverse section of B. tripartitus, showing the guard formed of three lon- 

 gitudinal portions : p. 60. 



Fig. 13. Transverse section of B. tripartitus, near the apex of the guard : p. 60. 



Figs. 14 & 15. Belemnites ellipticus, from Dundry : these two parts fit together: 

 p. 60. 



Fig. 16. Transverse section of B. ellipticus : p. 60. 



Fig. 17. Belemnites ellipticus, var. a. 



Fig. 18. Belemnites electrinus : p. 61. 



Figs. 19 & 20. The two longitudinal portions, forming the guard of the Belemnites 

 electrinus (see p. 61.) ; showing in the centre the canal formed by decomposition, 

 and at the apex of Jig. 19 the mamillated and conical point, — separated from 

 fig. 20, — in which last figure there has been left a corresponding cavity, which, 

 when found separate, led to the erroneous notion of the Belemnite having two 

 conic chambered shells. 



Fig. 21. Outline of the impression of the blood-vessels on the guard of Belemnites 

 electrinus : p. 61. 



Fig. 22. Belemnites fusiformis : p. 61. 



Plate IX. 



Fig. 1. Fragments of B. electrinus (p. 61), showing an induration formed in the 

 canal resulting from decomposition, and exposed by the separating and falling 

 out of a portion of the laminae forming the guard. — This appearance occasioned 

 the erroneous impression that the Belemnite had a canal extending from the 

 siphunculus through the guard ; the projecting point being considered as having 

 been formed in the siphunculus. 



Fig. 2. Magnified representation of 2 nacrous laminae, having crystalline spiculaepro- 



