3^4 



NORTH AMERICAN INDEX FOSSILS. 



XI. Glossites Hall. 



Elliptical, with short anterior and large, rounded posterior 

 extremity. Beaks small and appressed. Hinge line long and 

 gently arcuate. Umbonal slope prominent only above. Surface 

 marked with fine concentric striae which often become lamellose. 

 Lunule distinct. Teeth doubtful. Ligament external. Muscular 

 impressions shallow. 



Distinguished from Modiomorpha by its regular elliptical outline 

 and by the presence of a lunule. Devonic. 



30. G. lingualis Hall. (Fig. 488, a.) Devonic. 



Length usually a little more than twice the height. 

 Chemung Group : New York, Pennsylvania. 



Fig. 488. a, Glossites lingualis, left valve ; &, c, Palatanatina typa, left and right 

 valves; d, Tellinopsis subemarginata ; e, Cardiopsis radiata. (N. Y. Surv. ) 



XII. Saffordia Ulrich. 



Rather small, transversely ovate, equivalve, and very inequi- 

 lateral, with beaks near the anterior extremity. Surface bearing 

 a moderate umbonal ridge and a more or less distinct depression 

 dorsally. Lunule and escutcheon present. One wedge-shaped 

 cardinal tooth and a posterior lateral tooth present in left valve 

 and corresponding cavities in the right. Resilifer present. Pal- 

 lial line simple. 



Differs from Cuneamya in the thicker shell, more distinct muscu- 

 lar impressions, arcuate posterior cardinal margin, and different 

 hinge characters ; from Grammysia in the teeth and in the greater 

 depth of the anterior muscle scar. Ordovicic. 



