69 



SUBKINGDOM MOLLUSCOIDA. 



ORDER LYOPOMATA. 

 Family LINGTJLIDiE. 



LINGTJLA INDIANENSIS, n. sp. 



Plate VII, Fig. 1, ventral valve. 



Subovate or nearly subelliptical in outline; greatest width 

 below the middle; length nine-tenths of an inch, greatest width 

 six-tenths of an inch, or one-half longer than wide. Apical 

 end somewhat truncated, anterior extremity more uniformly 

 rounded. Sides gently convex. Valves very moderately convex 

 in the central part and flattened near the margins. Beaks not 

 prominent. Color, light brown or yellowish brown. 



Concentric striae very fine near the beaks, and, therefore, in 

 the younger stages of growth but becoming coarser and more 

 distant and somewhat undulating toward the anterior end and 

 lateral margins. 



There is no described species from Subcarboniferous rocks 

 having the general form of this one, and it would not throw 

 any light upon it, to compare it with subovate or subelliptical 

 forms from Silurian or Devonian rocks. 



Found in the Keokuk Group, at Crawfordsville, Indiana, and 

 now in the collection of Wm. F. E. Gurley. 



