﻿Plate 
  17 
  

  

  All 
  figures 
  natural 
  size 
  

  

  Page 
  

   ABROTOCRINUS 
  TJNICUS 
  (Hall) 
  65,73 
  

  

  Fig. 
  1. 
  Anterior 
  view 
  of 
  complete 
  crown, 
  to 
  show 
  general 
  arrangement 
  of 
  

   arms, 
  and 
  pentagonal 
  stem. 
  

  

  2. 
  Posterior 
  view 
  of 
  calyx, 
  with 
  sac 
  completely 
  exposed. 
  

  

  3. 
  Anterior 
  view 
  of 
  crown 
  with 
  sac 
  exposed, 
  showing 
  anal 
  opening 
  

  

  midway, 
  and 
  spines 
  at 
  distal 
  end. 
  

  

  Keokuk 
  limestone 
  ; 
  Crawfordsville, 
  Indiana. 
  

  

  DECADOCRINUS 
  HALLI 
  (Hall) 
  65,91 
  

  

  Fig. 
  4. 
  Anterior 
  view 
  of 
  complete 
  crown, 
  showing 
  delicate 
  structure 
  of 
  

   species 
  in 
  the 
  earlier 
  formations. 
  

   5. 
  Posterior 
  view 
  of 
  a 
  similar 
  specimen. 
  

  

  Upper 
  Burlington 
  limestone 
  ; 
  Burlington, 
  Iowa. 
  

  

  DECADOCRINUS 
  TUMIDULUS 
  (Miller 
  and 
  GurleyK- 
  . 
  65,92 
  

  

  Fig. 
  6. 
  Posterior 
  view 
  of 
  crown, 
  with 
  tumid 
  basal 
  and 
  anal 
  plates, 
  and 
  

   inflated 
  distal 
  end 
  of 
  sac. 
  For 
  anal 
  opening 
  in 
  sac, 
  see 
  North 
  

   American 
  Crinoidea 
  Camerata, 
  pi. 
  7, 
  figs. 
  4. 
  5. 
  

   Keokuk 
  limestone; 
  Indian 
  Creek, 
  Indiana. 
  

  

  SCYTALOCRINUS 
  VALIDUS 
  Wachsmuth 
  and 
  Springer___ 
  ._ 
  65,92 
  

  

  Fig. 
  7. 
  Anterior 
  view 
  of 
  specimen 
  with 
  sac 
  completely 
  exposed, 
  and 
  anal 
  

   opening 
  midway 
  ; 
  arms 
  broken 
  off 
  about 
  half 
  way 
  up. 
  

   S. 
  Another 
  specimen 
  showing 
  full 
  length 
  of 
  arms, 
  and 
  single 
  arm 
  in 
  

   anterior 
  ray. 
  

  

  Keokuk 
  limestone; 
  Indian 
  Creek, 
  Indiana. 
  

   124 
  

  

  