PLATE XXII. 



Pentacrinus wyville-thomsoni, Jeffreys. 



Oue of the upper stem-joints, ..... 



The top stem-joint of a young specimen with a smaller one in- 

 terpolated above it, .... . 

 A small interpolated joint, ..... 

 Another interpolated joint, somewhat younger, 



An older joint from the upper part of the stem, with an impres- 

 sion on its upper surface in which rested the young joint 

 shown in fig. 4, . 



The upper face of a young nodal joint, 



7. A young iuternodal joint, ..... 



8. A somewhat older internodal joint, .... 



Figs. 9-12. Young internodal joints from the growing part of the stem, 

 with smaller ones interpolated above them at different stages 

 of development, ...... 



Fig. 13. An older, but still immature internodal joint, . 



Fig. 14. A young internodal joint from the upper part of the stem, 



Fig. 15. Upper face of a young nodal joint from the upper part of the 

 stem, ....... 



Fig. 16. Lower or syzygial face of a nodal joint from the middle of the 

 stem, ....... 



Fig. 17. Lower face of a supra-nodal joint from the upper part of the 

 stem, ....... 



Fig. 18. Upper face of the corresponding nodal joint, . 



Figs. 19-24. Mature joints from a little below the middle of the 



Fig. 19. Upper face of a nodal joint, . 



Fig. 20. Its lower or syzygial face, 



Fig. 21. The upper face of an infra-nodal joint, 



Fig. 22. Its lower face, .... 



Figs. 23, 24. Ordinary internodal joints, 



Figs. 25, 26. Old internodal joints from the lowest part of the stem. 



Fig. 27. An enlarged nodal joint from the end of the stem with its 

 lower face rounded and the central canal closed up, 



Fig. 28. Portion of the calcareous network forming the substance of the 

 stem-joints, 



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