PLATE XXV. 



ECHINOBRISSI FROM THE GrEAT OoLITE, AND CoRNBRASH. 



Great Oolite Species. 



]. a. EcHiNOBRissus Griesbachii, Wri(/ht, p. 340. Upper surface, natural size. 



b. Upper surface of the same, magnified twice. 



c. Under surface, natural size. 



d. Ditto, magnified twice. 



e. Lateral view of the test, natural size. 



/. Ambulacral area, poriferous zones, and inter-ambulacral plates, magnified four times. 



Cornbrash Species. 



2 a. EcHiNOBRissus ORBICULARIS, Phillips, p. 341. Upper surface, natural size. 



b. Under surface of the same test, natural size. 



c. Lateral view of ditto, showing the poriferous zones. 



d. Apical disc, with its internal complementary plates, magnified five times. 



e. Ambulacral area, poriferous zones, and inter-ambulacral plates, magnified thrice. 

 /. Lateral view of a conoidal variety of this species, from Northamptonshire. 



y. Upper surface of another specimen, showing a greater eccentricity of the apical disc, 

 a wider anal valley, and a larger vent. 



