PLATE LI. 



EcHiNocoNus GLOBULUS, Desor, 1842. 

 From the Upper Chalk. 



Fig. 1 a. Base of the test, natural size. The Rev. T. Wiltshire, F.G.S. (P. 230.) 



b. Posterior view do. do. do. 



c. Lateral do. do. do. do. 



EcHiNOCONUS CASTANEA, Brongniart, 1842. 

 From the Lower Chalk. 



Fig. 2 a. Upper surface of a large test, natural size. My collection. (P. 21.5.) 



b. Under do. do. do. 



c. Lateral view do. do. 



d. Posterior do., showing the position of the marginal vent. 



e. Inter-ambulacral and ambulacral plates, and poriferous zone, magnified four 



diameters. 

 /. Do. from basal region. 



(J. Apical disc. 

 3. A small test of the same species, natural size. 



