566 



NORTH AMERICAN INDEX FOSSILS. 



Like D. deweyi in shape, but thick-shelled and larger (diameter 

 about 1.5 inches). Concentric striae moderately distinct. 

 Fox Hills : Montana, Colorado. 



569. D. nebrascensis Meek and Hayden. Cretacic. 

 Lunule and escutcheon both prominent. Slightly smaller than 



D. ozvenanabut more nearly circular, the height being about seven 

 eighths the length. Pallial sinus narrowly rounded at apex. 



Fox Hills : Nebraska-Wyoming, Assiniboia, North Dakota ? 

 Pierre : South Dakota. 



570. D. lenticularis (Rogers). (Fig. 776.) Eocenic. 



Fig. 776. Dosiniopsis lenticularis, right valves and cardinal view, 

 X %. (Md. Surv.) 



Shell varying from moderately thin to heavy. Diameter about 

 2 inches or more. Type of genus. 

 Aquia : Maryland. 



CLXV. Tapes Megerle von Muhlfeld. 

 More or less elongate-oval, with narrow hinge plate, divergent 

 and often bifid cardinal teeth, no laterals, and a deep pallial sinus. 

 Differs from Venus in the absence of lateral teeth ; also the inner 

 margins of valves are smooth. Comanchic-Recent. 

 571. T. hilgardi Shumard. Comanchic-Cretacic. 



Benton (Eagle Ford) of Texas. Fredericksburg and Washita of 

 Mexico. 



CLXVI. Tellina Linne. 



Oval, transversely elongate, slightly inequivalve, compressed, 

 rounded anteriorly, angular and gaping posteriorly. Surface 

 marked with an oblique fold extending from the umbo to the 

 lower posterior border. Beaks more or less twisted. Margins of 

 valves smooth. Two cardinal teeth present in each valve and one 



