PLATE LII. 



EcHiNOCONUs suBROTUNDus, Montell, 1S22. 

 From the Lower Chalk. 



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



c. Lateral view, do. 

 b. Posterior do. do. 



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



e. Apical disc, do. 

 /. Portion of the basal plates, do. 



EcHiNocoNus ABBREviATUs, Desor, 1842. 

 From the Upper Chalk of Norfolk. 



Fig. 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. 



ff. Primary tubercle, magnified. 

 /'• Do. do. 



i. Apical disc do. 



