﻿GEOL. 
  SOC. 
  AM., 
  MEMOIR 
  76 
  

  

  PALMER, 
  PL. 
  1 
  

  

  HUXLEYIA, 
  BARBATIA, 
  NUCULA, 
  GLYCYMERIS, 
  AND 
  PHILOBRYA 
  

  

  