PLATE 32 C. 
Fig. 1. 171. 18. Onrtuis supyueata. (Pag. 129.) 
1 a. Ventral valve of a young specimen. 1b. Profile view of the same. 1c. Front view of the same. 
1 d. Dorsal valve of another specimen, with a deep sinus. 1 e. Front view of the same. 
1 f. Dorsal valve of an older specimen, showing the gibbous ventral valve projecting beyond the cardinal line. 
1 g. Front view of the same. 
1h. Dorsal valve of an old individual. 
17. Front view of the same, showing the deep sinus of the dorsal valve, and the corresponding elevation on 
the opposite valve. 
1k, m. Cardinal views of young and old individuals. 1 nm. View of the ventral valve. 
Fig. 2. 170. 17. Onrrtuis sINUATA. (Pag. 128.) 
21,m. Cardinal views of young and old specimens. 
2n, 0. 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. 
2q, 7. The two lower figures show a slight difference in the character of the visceral impression. 
2s. 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. 
