﻿Plate 
  23 
  

  

  All 
  figures 
  natural 
  size 
  

  

  Page 
  

   ZEACRINUS 
  WORTHENI 
  Hall 
  SI 
  

  

  Fig. 
  1. 
  Typical 
  specimen, 
  posterior 
  view, 
  showing 
  the 
  usual 
  contour 
  

   of 
  crown 
  with 
  arms 
  closely 
  folded; 
  narrow 
  anal 
  area 
  with 
  

   small 
  basals, 
  posterior 
  basal 
  acuminate, 
  and 
  RA 
  occupying 
  

   entire 
  width 
  of 
  area 
  above 
  it, 
  as 
  occurs 
  in 
  55 
  per 
  cent 
  of 
  the 
  

   specimens. 
  

  

  2. 
  Posterior 
  view 
  of 
  a 
  similar 
  specimen, 
  with 
  like 
  narrow 
  anal 
  area 
  

  

  and 
  small 
  basals. 
  

   2a. 
  Anterior 
  view 
  of 
  same 
  with 
  three 
  rays 
  removed, 
  exposing 
  three 
  

   sides 
  of 
  the 
  pyramidal 
  ventral 
  sac, 
  with 
  anal 
  opening 
  midway. 
  

  

  3. 
  L. 
  ant. 
  view 
  of 
  specimen 
  with 
  sac 
  completely 
  exposed, 
  showing- 
  

  

  opening 
  midway 
  at 
  anterior 
  side 
  ; 
  apex 
  of 
  pyramid 
  broken 
  off. 
  

  

  4. 
  Posterior 
  view 
  of 
  another 
  specimen 
  with 
  sac 
  intact; 
  narrow 
  anal 
  

  

  area 
  with 
  sharp 
  ridge-like 
  succession 
  of 
  plates 
  following 
  it. 
  

  

  5. 
  Distal 
  view 
  of 
  sac 
  of 
  another 
  specimen 
  vertically 
  compressed, 
  

  

  with 
  apex 
  broken. 
  

   G. 
  Basal 
  view 
  of 
  a 
  typical 
  specimen 
  with 
  the 
  usual 
  form 
  of 
  anal 
  

   area. 
  

  

  7. 
  Posterior 
  view 
  of 
  specimen 
  with 
  another 
  form 
  of 
  narrow 
  anal 
  

  

  area. 
  

  

  8. 
  Basal 
  and 
  posterior 
  view 
  of 
  maximum 
  specimen 
  with 
  post, 
  basal 
  

  

  truncate, 
  and 
  anal 
  area 
  similar 
  to 
  that 
  of 
  Z. 
  magnoliaeformis 
  ; 
  

   distribution 
  of 
  arms 
  is 
  well 
  shown. 
  

  

  Upper 
  Chester. 
  Clen 
  Dean 
  formation; 
  Sloan's 
  Valley, 
  

   Kentucky. 
  

  

  ZEACRINUS 
  GIRTYI. 
  new 
  species. 
  _ 
  84 
  

  

  Fig. 
  9. 
  Posterior 
  view 
  of 
  type, 
  showing 
  wide 
  anal 
  area, 
  truncate 
  post. 
  

   B, 
  with 
  RA 
  short 
  and 
  broad; 
  and 
  form 
  and 
  proportions 
  of 
  

   club-shaped 
  sac 
  

   9a. 
  Anterior 
  view 
  of 
  same, 
  showing 
  complete 
  succession 
  of 
  arms, 
  and 
  

   rounded 
  distal 
  end 
  of 
  sac 
  rising 
  beyond 
  their 
  extremities. 
  

   Pennsylvanian. 
  Morrow 
  formation; 
  Crittenden, 
  Oklahoma. 
  

   130 
  

  

  