﻿GEOL. 
  SOC. 
  AM., 
  MEMOIR 
  76 
  

  

  PALMER, 
  PL. 
  18 
  

  

  LITTORINA, 
  LACUNA, 
  PHASIANELLA, 
  MARGARITES, 
  ACMAEA, 
  LEPETA. 
  

   PUNCTURELLA, 
  AND 
  FISSURELLA 
  

  

  