﻿Plate 
  19. 
  

  

  All 
  figures 
  natural 
  size 
  

  

  Page 
  

   AITLOCRINUS 
  AGASSIZI 
  Wachsmuth 
  and 
  Springer 
  67 
  

  

  Fig. 
  1. 
  Anterior 
  view 
  of 
  specimen 
  with 
  sac 
  complete, 
  doubled 
  upon 
  itself 
  

   and 
  projecting 
  downward 
  in 
  form 
  of 
  a 
  spout, 
  at 
  the 
  end 
  of 
  

   which 
  is 
  the 
  anal 
  opening 
  ; 
  the 
  place 
  of 
  bending 
  marked 
  by 
  

   spinous 
  nodes. 
  

  

  2. 
  Lateral 
  view 
  of 
  another 
  specimen 
  with 
  sac 
  complete, 
  showing- 
  

  

  its 
  full 
  curvature 
  leading 
  to 
  the 
  spout. 
  Note 
  the 
  longitudinal 
  

   ridges, 
  which 
  can 
  be 
  traced 
  the 
  full 
  length 
  of 
  the 
  sac 
  upward 
  

   and 
  following 
  the 
  curve 
  down 
  again 
  into 
  the 
  spout, 
  the 
  number 
  

   of 
  ridges 
  being 
  correspondingly 
  increased 
  in 
  the 
  doubled 
  part. 
  

   2a. 
  Posterior 
  view 
  of 
  same 
  specimen, 
  showing 
  the 
  anal 
  plates, 
  and 
  

   the 
  sharp 
  angular 
  sculpture 
  of 
  the 
  calyx. 
  

  

  3. 
  Distal 
  portion 
  of 
  another 
  specimen, 
  showing 
  in 
  greater 
  detail 
  

  

  the 
  same 
  structures 
  as 
  the 
  his!. 
  

  

  4. 
  Posterior 
  view 
  of 
  another 
  specimen, 
  showing 
  the 
  sac 
  complete 
  

  

  to 
  the 
  point 
  of 
  bending, 
  marked 
  by 
  spinous 
  nodes, 
  and 
  the 
  

   distal 
  end 
  of 
  the 
  spout 
  which 
  projects 
  from 
  the 
  opposite 
  side 
  ; 
  

   the 
  sharp 
  sculpture 
  of 
  the 
  anal 
  and 
  other 
  calyx 
  plates 
  ; 
  and 
  

   the 
  pores 
  with 
  which 
  the 
  hexagonal 
  tube 
  plates 
  are 
  profusely 
  

   perforated 
  at 
  the 
  middle 
  of 
  their 
  sides. 
  

  

  5. 
  Anterior 
  view 
  of 
  specimen 
  with 
  arms 
  in 
  place 
  to 
  their 
  full 
  length. 
  

  

  showing 
  their 
  proportions 
  and 
  the 
  character 
  of 
  the 
  pinnules. 
  

   Keokuk 
  limestone; 
  Indian 
  Creek, 
  Indiana. 
  

   126 
  

  

  