^ 



PLATE 32 C. 



Fig. 1. 171. 18. Okthis subtooata. (Pag. 129.) 



1 a. Ventral valve of a young specimen. 1 6. Profile view of the same. 1 e. Front view of the same. 

 1 d. Dorsal valve of another specimen, with a deep sinus. 1 e. Front view of the same. 



1 /. Dorsal valve of an older specimen, showing the gibbons ventral valve projecting beyond the cardinal line. 

 1 g. Front view of the same. 

 I k. Dorsal valve of an old individual. 



1 t. Front view of the same, showing the deep sinus of the dorsal valve, and the corresponding elevation on 

 the opposite valve. 



1 At, m. Cardinal views of young and old individuals. 1 n. View of the ventral valve. 



Fig. 2. 170. 17. Orthis sinttata. (Pag. 128.) 



3 /, m. Cardinal views of young and old specimens. 

 .2 n, o. Ventral valves of a young and old specimen. 



2 p. Interior of the dorsal valve, showing the form of the visceral impression, and the radii near the margin. 

 2 q, r. The two lower figures show a slight difference in the character of the visceral impression. 



2 (. Interior of the ventral valve, showing the medial tooth, which is thicker and stronger than in the last 

 species, and is connected with a strong medial ridge which is trifid below. 



