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AMERICAN TERTIARY AND CRETACEOUS FOSSILS. 393 



DENTALIUM, Linn. 



D. Ripleyanum. PI. 68, fig. 17. Very slightly arcuate, moderately thick, surface 

 marked by faint longitudinal ribs especially on the inner side of the curve and by ob- 

 solete lines, crossed by circular lines of growth. 



Dimensions. — Length of fragment - 5 in., greatest external diameter *15 in. 



Locality. — Eufala, Alabama. Ripley Group. 



PHOLAS, Linn. 



P. cretaceA. PI. 68, fig. 18. Tube conical, rounded at the widest end, surface 

 marked by oblique lines ; shell ? 

 Dimensions. — Length of tube 1 in., diameter (greatest) *35 in. 

 Locality. — Raritan Bay, N. J., in wood, and replaced by pyrites. 

 Collection of the Academy. 



TEREDO, Linn. 



T. irregularis. PI. 68, fig. 19. Tube irregular, tortuous, dilated in places and 

 sometimes transversely wrinkled. 



Shell twice as large as that of T. tibialis, more abruptly truncate anteriorly. I have 

 been able to see but a small portion of the shell of this species. It is imbedded in the 

 portion of the tube figured. Collection of the Academy. 



GASTROCHAENA, Spmgl. 



G. Americana. PI. 68, fig. 20. Elongated conical; transversely wrinkled; termi- 

 nation of widest end, round. 



Dimensions. — Length 2*5 in., greatest diameter - 5 in. 



Locality. — Common in the yellow limestone of Timber Creek, and found with the 

 above species in the brown marl of Burlington Co., N. J. 



ISOCARDIA, Lam. 



I. Conradi. PL 68, fig. 21. Triangular, equivalve; beaks large, inclined anteri- 

 orly ; umbones large ; anterior margin nearly straight, basal sinuate, posterior sub- 

 angular below, nearly straight above ; surface marked by fine concentric lines. 



Dimensions. — Length LI in., width L4 in., diameter 1 in. 



Locality. — Prairie Bluff, Ala., and Timber Creek, N. J. Casts. 



VENUP, Lim. 



V. Ripleyana. PL 68, fig. 22. Inequilateral; beaks small, anterior; cardinal 



100 



