PLATE XIII. 

 From the White Chalk. 



CiDARIS CLAVIGERA, KunU/, 1822. 



Fig. 1 a. Test and spines, natural size. (P. 71.) 



b. Spine of same, magnified. 

 Fig. 2. Spine of same, natm-al size. 

 Fig. 3 a. Test and spines, natural size. (P. 71.) 



b. Spine of same, natural size. 



c. Spine of same, magnified. 



Fig. 4 a. Test and spines, natural size. (P. 71.) 



b. Spine of same, magnified. 

 Fig. 5 a. Spine of C. davigera, of elongate form, natural size. (P. 71.) 



b. The same, magnified. 



From, the Lower Chalk. 



Fig. 6 a. Plates of Cidaris dissimiles, Forb. (P. 46.) 



b. One of the plates, magnified. All the above are from the Cabinet of the Rev. 

 Thomas Wiltshire, F.G.S. 

 Fig. 7 a. Spine of Cidaris pleracantha ? natural size. Collection of J. R. Capron, Esq., 

 F.G.S. 

 b. The same, magnified. (P. 67.) 

 Figs. 8, 9, 10. Spines of Cidaris Bowerbankii, Forb. Collection of Rev. T. Wiltshire, 



F.G.S. fP. 77.) 

 Fig. 11. Do. do. Do. J. R. Capron, Esq., F.G.S. 



Fig. 13 a. Do. natural size. Cabinet of Rev. Thomas Wiltshire, F.G.S. 



b. Head and neck of same, magnified. 

 Fig. 14. Spine of same, natiu-al size. Cabinet of Rev. Thomas Wiltshire, F.G.S. 



