﻿922 
  POLOGI 
  OP 
  ELLINOIE 
  

  

  Surface 
  of 
  the 
  valves 
  marked 
  by 
  numerous 
  raised 
  lines 
  or 
  a 
  

   that 
  increase 
  towards 
  the 
  base 
  by 
  implantation, 
  and 
  arc 
  about 
  as 
  

  

  wide 
  as 
  the 
  spaces 
  between 
  thein. 
  From 
  BO 
  to 
  90 
  of 
  tl 
  

   may 
  be 
  counted 
  on 
  the 
  borders 
  of 
  the 
  shell. 
  

   Greatest 
  width 
  of 
  the 
  valves 
  1 
  inches. 
  Length 
  from 
  beak 
  to 
  I 
  

   inches. 
  Length 
  of 
  hinge-line 
  Bj 
  inches. 
  

   lUty 
  and 
  position 
  .- 
  l"pi)er 
  beds 
  of 
  the 
  Keokuk 
  lim. 
  

   Warsaw, 
  111. 
  The 
  author's 
  collect 
  ion. 
  

  

  This 
  is 
  a 
  very 
  rare 
  species, 
  only 
  one 
  valve, 
  and 
  part 
  of 
  another. 
  

   haying 
  been 
  found 
  in 
  26 
  years 
  collections 
  from 
  this 
  horizon. 
  

  

  