﻿PLATE LII 



Echinoconus subrotundus, Mantett, 1822. 

 From the Lower Chalk. 



1 a. Base of test, natural size. Rev. T. Wiltshire, F.G.S. (P. 219.) 



c. Lateral view, do. 

 b. Posterior do. do. 



d. Tnter- ambulacra, ambulacra, and poriferous zones, magnified four times. 



e. Apical disc, do. 

 /. Portion of the basal plates, do. 



Echinoconus abbreviates, Desor, 1842. 

 From the Upper Chalk of Norfolk. 



2 a. Upper surface of the test, natural size. My collection. (P. 226.) 



b. Base do. do. 



c. Lateral view do. do. 



d. Posterior do., with recurved vent. 



e. Inter-ambulacra, ambulacra, and zones, magnified four diameters. 

 /. Portion of the basal plates, do. do. 



g. Primary tubercle, magnified. 



h. Do. do. 



i. Apical disc do. 



