PLATE VII a. 

 Cidaris sceptrifera, Mantett, 1822. 



From the White Chalk. 



Fig. 



1 a. Test and spines, C. sceptrifera, var. jilosa, from the White Chalk of Gravesend. natural 

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



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



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



3. Spine of C. sceptrifera, var. filosa, belonging to the Rev. Thos. Wiltshire, F.G.S. 



Cidaris perornata, Forbes, 1850. 



From the WJiite Chalk. 



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

 specimen, now in his cabinet. P. 62. 

 b. Lateral view of the same. 



