GASTROPODA— CERITHUDM. 



747 



Family Cerithiid/E Menke. 

 CXXXIII. Bittium Leach. 

 Turreted shells with spirals and costae which generally cancel- 

 late each other. Aperture with short, straight canal and sharp 

 outer lip. Jurassic-Recent. 



477. B. permutabile Dall. (Fig. 1082, c.) Oligocenic. 

 Greatest convexity of the whorls below the middle of the ex- 

 posed part ; costae strong but becoming obsolescent towards the 

 suture ; spiral fine, often compound. Aperture with feeble canal. 



Chipolan marls of Florida. 



478. B. cossmannii Dall. (Fig. 1082, b.) Oligocenic. 



FlG. 1082. a, Bittium (Sty/iferina) boiplex, X 7»5 '■> b, Bittiut// cossthamui, X32^ > 

 c, B. permutabile, X 4* 6- 



Shorter and stouter than preceding, rather inflated, with ribs 

 mostly obsolete on adult whorls except here and theie a strong 

 varix-like one. 



Chipolan marls of Florida. 

 479. B. (Styliferina) boiplex Dall. (Fig. 1082, a.) Oligocenic. 



Long, slender, round-whorled ; three strong spirals cancellating 

 the ribs ; occasionally strong varix-like ribs ; simple spirals on 

 body of last whorl, and sometimes above suture. Aperture witn- 

 out canal. 



Chipolan marls of Florida. 



