PLATE LXXIV. 



Holaster suborbicularis, Defrance. 



From the Chloritic Marl. 



Fig. 1 a. Upper surface, natural size. My collection. (P. 314.) 



b. Under surface do. 



c. Lateral view do. 



d. Anterior do. do. 



e. Posterior do. do. 



Holaster trecensis, Leymerie. 

 From the Lotver and Grey Chalk. 



Pig. 2 a. Upper surface, natural size. My collection. (P. 323.) 



b. Under do. do. 



c. Lateral view do. 



d. Anterior do. do. 



e. Posterior border showing the position of the periprocte. 



