PLATE IV b—C ontinued. 
DINOBOLUS, Hall. 
Page 36. 
Dinobolus Conradi, Hall. 
Fig. 13. An internal cast of a brachial valve, indicating very distinctly the muscular impressions and the 
minute platform-vaults. 
Niagara limestone. G-rafton, Wisconsin. 
Fig. 14. An internal cast of a young pedicle-valve; showing the close approximation of the platform-vaults. 
Niagara limestone. NmT~heGl^iam r L.<ma. \ s v I (' t': 
Fig. 15. An internal cast of a pedicle-valve ; indicating the duplicate platform-vaults. 
Niagara limestone. Racine, Wisconsin. 
Fig. 16. An internal cast of a pedicle-valve in which the vaults of the platform attained unusual length. 
Fig. 17. The counterpart of the same ; from a gutta-percha impression. 
Niagara limestone. Near LeClaire, Iowa, 
Fig. 18. A transverse section of a shell near the anterior edge of the platform. we V 
Fig. 19. An internal cast of the pedicle-valve, retaining very distinctly the median and lateral muscular 
scars and the impression of the crescent. 
Fig. 20. The counterpart of the same, from a gutta-percha impression ; showing the usual size and char¬ 
acter of the deltidium. 
Niagara limestone. LeClaire, Iowa. 
Fig. 21. The interior of a pedicle-valve, having the deltidium extremely developed. From a gutta-percha 
impression of a natural cast. 
Niagara limestone. Near LeClaire, Iowa. 
Fig. 22. An internal cast of a brachial valve, the umbonal cavity of which has been filled by thickening of 
the shell. 
Niagara limestone. • LeClaire, Iowa. 
Fig. 23. An internal cast of a large brachial valve, with the muscular impressions sharply defined. 
Niagara limestone. Racine, Wisconsin. 
Fig. 24. An internal cast of a brachial valve; showing the unsymmetrical development of the vaults of 
platform, two on one side and three on the other. 
Niagara limestone. LeClaire, Iowa. 
