PLATE II. 



Cidaris from the Coralline Oolite. 

 Fig. 



1 a. Cidaris Smithii, Wright, p. 50. Under surface of tlae test, natural size, showing 



the jaws in situ. 



b. Lateral view of another specimen, natural size. 



c. One inter-ambulacral plate, and a portion of an ambulacral area, with the 



poriferous zones, magnified two diameters. 



d. Inter-ambulacral plate, with its primary tubercle seen in profile, and magnified two 



diameters. 



e. Fragment of a spine attached to the test " a" magnified two diameters. 



2 a. Cidaris florigemma, Phillips, p. 44. Test with spines attached, on a slab of 



Coralline Oolite. 



b. A large test, natural size, showing the base and mouth opening. 



c. Lateral view of the same test, natural size. 



d. Primary spines of Cidaris florigemma, natural size. 



e. Head, neck, and acetabulum of the same, magnified two diameters. 

 /. Small, spatulate, secondary spines, magnified three and a half times. 



g. One inter-ambulacral plate, and a portion of an ambulacral area with the poriferous 

 zones ; magnified two diameters. 



