PLATK IV B— Coutiiiueil. 



DINOBOLUS, Hall. 



Page 36. 



DiNOBOLUS CONRADI, Hull. 



Fig. 13. All internal cast of a bniehial valve, indicating very distinctly the nuisculai- impressions ami tlie 

 minute platform-vaults. 



Niagara limestone. G-rafton, Wisconsin. 

 Fig. 14. An internal cast of a yovmg pedicle-valve ; showing the close approximation of the platform-viuilts. 



Niagara limestone. Near LeClaire, Iowa. 

 Fig. l.T. An internal cast of a pedicle-valve ; indicating the duplicate platform-vaults. 



Niagara limestone. Racine, Wisconsin. 

 Fig. Iti. An internal cast of a jiedicle-valve in which the vaults of the platform attained nnnsual length. 

 Fig. 17. The counterpart of the same ; from a gutta-percha impi-ession. 



Niagara limestone. Near LeClaire, Iowa, 

 Fig. 18. A ti'ansverse section of a shell near the anterior edge of the platform. 

 Fig. lil. An internal ca-st of the pedicle-valve, retaining very distinctly the median and lateral muscular 



scars and the impression of the crescent. 

 Fig. '2,0. 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 h;is been filled by thickening of 

 the shell. 



Niagara limestone. LeClaire, Iowa. 

 Fig. 23. An internal ca.st of a large brachial valve, with the muscnilar impi'essions shai'ply ilefined. 



Niagara limestone. Racine, Wi.icoii.sin. 

 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, loica. 



