﻿Plate 
  22 
  

  

  All 
  figures 
  natural 
  size 
  

  

  Page 
  

   ZEACRINUS 
  COMMATICUS 
  S. 
  A. 
  Miller 
  _„_ 
  65,80 
  

  

  Pig. 
  1. 
  Posterior 
  view 
  of 
  complete 
  crown, 
  showing 
  mode 
  of 
  arm 
  branch- 
  

   ing, 
  nodose 
  distal 
  end 
  of 
  sac 
  projecting 
  beyond 
  arms, 
  and 
  

   arrangement 
  of 
  anal 
  plates 
  as 
  usually 
  seen. 
  

  

  2. 
  Left 
  anterior 
  view 
  of 
  another 
  specimen 
  with 
  sac 
  partially 
  

  

  exposed, 
  showing 
  the 
  increased 
  number 
  of 
  IBr 
  in 
  anterior 
  

   ray. 
  

  

  3. 
  Specimen 
  exposing 
  full 
  length 
  of 
  club-shaped 
  sac, 
  from 
  the 
  

  

  posterior 
  side, 
  showing 
  complete 
  succession 
  of 
  plates 
  from 
  

   the 
  anal 
  area 
  up. 
  

   3d. 
  Anterior 
  view 
  of 
  same, 
  showing 
  anal 
  opening 
  at 
  base 
  of 
  sac. 
  

   Keokuk 
  limestone, 
  upper 
  part: 
  Boonville, 
  Missouri. 
  

  

  ZEACRINUS 
  MAGNOLIAEFORMIS 
  (Troost) 
  Hall 
  ___ 
  SI 
  

  

  Fig. 
  4. 
  A 
  maximum 
  specimen, 
  seen 
  from 
  the 
  posterior 
  side, 
  showing 
  

   form 
  and 
  proportions 
  of 
  crown, 
  and 
  arrangement 
  of 
  anal 
  

   plates 
  as 
  usually 
  found. 
  

  

  5. 
  A 
  medium 
  sized 
  specimen; 
  anterior 
  view 
  of 
  complete 
  crown. 
  

  

  showing 
  the 
  usual 
  arrangement 
  of 
  arms. 
  

  

  6. 
  Lower 
  part 
  of 
  crown 
  of 
  smaller 
  specimen, 
  from 
  the 
  posterior 
  

  

  side, 
  showing 
  anal 
  plates. 
  

  

  7. 
  Basal 
  view 
  of 
  detached 
  calyx, 
  with 
  typical 
  arrangement 
  of 
  broad 
  

  

  anal 
  area, 
  as 
  seen 
  in 
  about 
  80 
  per 
  cent 
  of 
  the 
  specimens: 
  KA 
  

   elongate 
  and 
  passing 
  down 
  into 
  the 
  basal 
  ring, 
  and 
  post. 
  

   B 
  truncate: 
  BB 
  large. 
  

  

  S. 
  Similar 
  view 
  of 
  calyx 
  with 
  narrow 
  anal 
  area, 
  as 
  found 
  in 
  aboul 
  

   12 
  per 
  cent 
  of 
  the 
  specimens; 
  RA 
  short, 
  and 
  post. 
  B 
  acu- 
  

   minate, 
  not 
  connecting 
  with 
  succeeding 
  plate 
  

  

  9. 
  Another 
  variation 
  of 
  the 
  narrow 
  anal 
  area. 
  BB 
  elongate, 
  petal 
  

   shaped, 
  as 
  in 
  most 
  of 
  the 
  specimens. 
  

  

  10. 
  Basal 
  view 
  of 
  calyx 
  with 
  broad 
  anal 
  side, 
  showing 
  I 
  KB, 
  and 
  

  

  BB 
  entirely 
  within 
  the 
  cavity, 
  exceptionally 
  small. 
  

  

  11. 
  Interior 
  view 
  of 
  calyx, 
  showing 
  the 
  cone 
  of 
  greatly 
  enlarged 
  

  

  infrabasals. 
  

   Upper 
  Chester, 
  Gasper 
  formation; 
  Huntsville, 
  Alabama. 
  

  

  ZEACRINUS 
  WORTHENI 
  Hall 
  ._ 
  65, 
  SI 
  

  

  Fig. 
  12. 
  Basal 
  view 
  of 
  specimen 
  with 
  broad 
  anal 
  area, 
  for 
  comparison 
  

   with 
  Z. 
  magnoliaeformis. 
  

  

  Upper 
  Chester. 
  (4lci> 
  Dean 
  formation: 
  Sloan's 
  Valley, 
  

   Kentucky. 
  

  

  L29 
  

  

  