PLATE VII a. 

 CiDARis scEPTRiFERA, Mantell, 1822. 



^ From the Wldte Chalk. 



Fig. 



1 u. Test and spines, C. sce2)irifera, xar.Jilosa, from the White Chalk of Gravesend, natural 

 size, presented to the British Museum by the Rev. Norman Glass, P.G.S. P. 54. 



/). Inter-ambulacral plate, ambulacra, and poriferous zones, magnified three diameters. 



r. A thickened variety of spine, magnified two diameters. 



'^. Spine of C. sceptrifera, var. Mom, belonging to the Rev. Thos. Wiltshire, F.G.S. 



CiDARis PERORNATA, Forbes, 1850. 



From the Wldte Chalk. 



2 a. Under surface of a large C. perornata, restored from the Rev. Thos. Wiltshire's 

 specimen, now in his cabinet. P. 62. 

 h. Lateral view of the same. 



