PLATE III. PLATYSTROPHIA TRICENARIA. Page 73. Fig. 1. Horizontal section of a portion, including two of the radii, and showing the fibrous non-punctate character of the shell. Fig. 4. Section showing the fibrous structure of the shell, and the large scat tered punctæ. PLATYSTROPHIA FLABELLA. Page 73. Fig. 5. A section including two of the interradial areas. The lower right hand portion has been cut through to the surface of the shell and shows the concentric striæ. Fig. 6. ORTHIS PERVETA. Page 73. Section showing the rows of minute punctæ. ORTHIS CLYTIE. Fig. 7. Showing the single and double rows of punctæ between the fibrous interspaces. ORTHIS ELEGANTULA. Page 73. Fig. 8. Showing somewhat obscurely the broad rows of punctæ. Fig. 9. Horizontal section of the shell through a varix of growth; the punctæ are partially obliterated by the action of the crystallization of iron pyrite. |