﻿114 
  Twenty-eighth 
  Eeport 
  on 
  the 
  State 
  Museum. 
  

  

  equal 
  to 
  two-thirds 
  the 
  height 
  from 
  the 
  base 
  of 
  the 
  arms 
  to 
  

   the 
  summit. 
  Basal 
  plates 
  covered 
  by 
  the 
  column. 
  First 
  radial 
  

   plates 
  strong, 
  the 
  greater 
  portion 
  of 
  their 
  height 
  visible 
  exter- 
  

   ior 
  to 
  the 
  column 
  ; 
  second 
  and 
  third 
  radials 
  wider 
  than 
  high. 
  

   Arms 
  attaining 
  their 
  full 
  width 
  near 
  the 
  base, 
  and 
  continuing 
  

   of 
  the 
  same 
  width 
  to 
  about 
  the 
  middle 
  of 
  their 
  length, 
  and 
  

   thence 
  gradually 
  tapering 
  to 
  the 
  summit. 
  The 
  solid 
  inter- 
  

   brachial 
  plates 
  narrow 
  in 
  the 
  lower 
  and 
  middle 
  part, 
  and 
  

   greatly 
  expanded 
  at 
  the 
  summit. 
  

  

  Column 
  strong, 
  composed 
  of 
  thick 
  joints 
  with 
  rounded 
  

   margins, 
  alternating 
  with 
  an 
  equal 
  number 
  of 
  much 
  thinner 
  

   joints 
  with 
  flattened 
  edges. 
  

  

  I 
  have 
  identified 
  this 
  species 
  with 
  the 
  E. 
  ovalis 
  of 
  Troost,. 
  

   from 
  a 
  comparison 
  of 
  the 
  original 
  specimens, 
  which 
  in 
  the 
  

   better 
  preserved 
  individuals 
  have 
  the 
  same 
  form 
  and 
  propor- 
  

   tions. 
  It 
  differs 
  from 
  the 
  young 
  of 
  E. 
  crassus 
  in 
  the 
  regu- 
  

   larly 
  elliptical 
  outline 
  of 
  the 
  entire 
  body, 
  the 
  curving 
  of 
  the 
  

   sides 
  of 
  the 
  calyx, 
  the 
  less 
  incurvation 
  of 
  the 
  first 
  radial 
  

   plates 
  into 
  the 
  column 
  cavity, 
  which 
  is 
  proportionally 
  smaller 
  

   than 
  in 
  that 
  species. 
  It 
  is 
  also 
  especially 
  distinguished 
  

   from 
  both 
  E. 
  ccelatus 
  and 
  E. 
  crassus, 
  by 
  the 
  great 
  expan- 
  

   sion 
  of 
  the 
  interbrachial 
  plates 
  upon 
  the 
  summit, 
  if 
  such 
  fea- 
  

   tures 
  are 
  to 
  be 
  regarded 
  as 
  of 
  specific 
  value. 
  

  

  Compare 
  fig. 
  13 
  of 
  plate 
  17, 
  with 
  figs. 
  5 
  and 
  7 
  of 
  plate 
  16, 
  

   and 
  with 
  figs. 
  5 
  and 
  7 
  of 
  plate 
  18. 
  

  

  Roots 
  Of 
  EUCALYPTOCRINUS. 
  

   Plate 
  19, 
  Figs. 
  6-8; 
  and 
  Plate 
  20. 
  

  

  The 
  condition 
  of 
  the 
  ancient 
  ocean 
  bed 
  in 
  the 
  region 
  of 
  

   county 
  now 
  occupied 
  by 
  central 
  Indiana, 
  was 
  apparently 
  

   one 
  of 
  the 
  most 
  quiet 
  and 
  sheltered 
  situations 
  known 
  during 
  

   the 
  Silurian 
  period, 
  and 
  life 
  was 
  as 
  prolific 
  as 
  in 
  any 
  tropical 
  

   region 
  of 
  the 
  present 
  day. 
  

  

  Large 
  surfaces 
  of 
  the 
  more 
  calcareous 
  layers 
  are 
  covered 
  

   with 
  numerous 
  forms 
  of 
  Bryozoa 
  and 
  corals 
  ; 
  and 
  the 
  abun- 
  

   dant 
  roots 
  of 
  Crinoidea, 
  with 
  the 
  bases 
  of 
  the 
  stems, 
  still 
  re- 
  

   main 
  as 
  they 
  grew 
  upon 
  the 
  muddy 
  bottom, 
  the 
  roots 
  pene- 
  

   trating 
  the 
  ancient 
  deposit, 
  or 
  commencing 
  their 
  growth 
  upon 
  

   some 
  other 
  organic 
  body, 
  and 
  not 
  unfrequently 
  upon 
  the 
  

   bodies 
  of 
  the 
  same 
  species, 
  or 
  others 
  of 
  the 
  genus 
  which 
  have 
  

  

  