PLATE I. 



Fig. 



1. Biflustra delicatula (recent). 



2. „ „ (fossil), p. 72. 



3. Flustra (?) dubia, p. 131. 



4. Biflustra delicatula, p. 72. 



a. Posterior aspect of lamina. 



b. Horizontal section. 



c. Longitudinal section. 



5. Hippothoa patac/onica, p. 24. 



6. 8crupocellaria scruposa (?) p. 19. 



7. Hippothra deniata, p. 26. 



a. Mao;nifled 25 diameters. 



b. Magnified 50 diameters. 



8. Crisia denticulata, p. 93. 



