FIG. i. 

 2. 

 3. 



4. 

 5. 



6. 



7. 



8. 



9. 



10. 

 11. 

 12. 

 13. 

 14. 

 15. 

 16. 

 17. 

 18. 

 19. 

 20. 

 21. 

 22. 

 23. 



24. 



25. 

 36. 

 27. 

 28. 



29. 

 30. 

 31. 

 32. 

 33. 

 34. 

 35. 

 36. 

 37. 

 38. 

 39. 

 40. 

 41. 



PLATE XIII. 



Vertebrae of encrini, or trochitae of different kinds. 



A series of vertebrae, in which is shewn the kind of motion of which these bodies 

 are capable. 



A distorted column, with the marks of attachment of vertebral processes. 



The screw-stone, or pully-stone, being the cast in the hollow of a series of vertebra?. 



The articulating surfaces of different encrinal vertebrae. 



The tortoise encrinite 

 f The articulating surfaces of different encrinal vertebrae. 



A series of vertebrae. 



A single plate belonging to the tortoise encrinite. 



The stag's horn encrinite. 



A series of oval vertebrae. 



A vertebra with a curious articulating surface. 



The straight encrinite. 



A vertebrae of the straight encrinite. 



r An asterial fossil from America; probably of the nature of the encrinus. 



The apparent base of the stag's-horn encrinus. 

 Branches of the stag's-horn encrinite. 

 An oval vertebra. 



A vertebra of the same animal, shewing the articulating surfaces crossing each 

 other, and thus allowing a total change in the position of the different parts of 

 the vertebral column. 



'Parts of different vertebral columns of encrini. 



