seoonflarieB, Th^ smaller of the tvvo immatujre left valves at hanri. 

 displays some of the charaoters of diip Planus ; it has more numer- 

 ous spinose ribs than the larger, '.vithout radial : '"ions on 

 the secondaries, but, on the other hand, the outline is that o." 

 bostryohites and there is no trace of concentric striation. 



Occurrenoe .- Up^er Olig'ocene: TTampa silex beds, Florida 

 (Dall, 1898, 1915); Tlimestone of V/hite Beach, -lorida (Ball, 

 1898, 1915); Sr.nto ^omin^o (Sowerby, 1850; Guppy, 1867, 1874; 

 '"xabb, 1873; Dall, 1898, 1915); Antigua (Oooke, ); Anp-uilla 



(Gur)ny, 1874; Dall, 1898, 1915); Lower Liocene : ■;3ov.den 



beds, BoTden, Jamaica (Gu^-oy, 1874; Dall, 1898, 1915U 



