PLATE XII. 



Fig. 

 1. Retepora cellulosa, p. 74. 



a. Anterior surface, magnified 25 diameters. 



b. Anterior surface, magnified 50 diameters. 

 V . Posterior surface, magnified 25 diameters. 



c. Fragment (natural size). 

 :2. R. Beaniana, p. 75. 



3. R. simplex, p. 76. 



a, d, <?,/. Anterior surface, in different conditions of age and attrition, 



magnified 25 diameters. 



b, Anterior surface, magnified 50 diameters. 

 b' Posterior surface, magnified 50 diameters. 



c, c, c, c. Fragments (natural size). 



4. R. notopachys, p. 76. 



a. Anterior surface, magnified 25 diameters. 



b. Anterior surface, magnified 50 diameters. 

 b'. Posterior surface, magnified 5.0 diameters. 



c. Fragment (natural size). 



d. Section, magnified 25 diameters. 



5. 6, 7. R. Beaniana. 



21 



