PLATE IX. 



CiDARis niRUDO, Sorignet, 1850. 



From the White Chalk. 



Fig. 1 a. Test and spines natural size in the Collection of Henry Willett, Esq.,F.G.S. 

 (P. 64.) 



1 h. Lateral view of the same test, natural size. 



1 c. Small spine from the arabulacral tubercles, magnified three diameters. 

 Fig. 2 a. Upper surface of a test, natural size, belonging to the British Museum. 



2 h. Literambulacral plate, ambulacral area and poriferous zones of the same, mag- 



nified three diameters. 



2 c. Apical disc and anal plates of the same, natural size. 



2 d. One ovarial and two ocular plates of the same, magnified twice. 

 Fig. 3. Under surface of another test, natural size, belonging to the British Museum. 

 Fig. 4 a. Primary spine, natural size, belonging to the British Museum. 



4 b. Lower portion of the same, magnified three diameters. 



4 c. Upper portion showing its stellate termination, magnified three diameters. 



Fig. 5. Primary spine, magnified three times, in the collection of Rev. T. Wiltshire, 

 F.G.S. 



