﻿206 
  Twenty-eighth 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  jection 
  or 
  extension 
  of 
  the 
  walls. 
  In 
  structure 
  this 
  area 
  is 
  

   composed 
  of 
  spreading, 
  radiciform, 
  bifurcating 
  rays, 
  con- 
  

   nected 
  by 
  irregular 
  polygonal 
  plates. 
  The 
  basal 
  rays 
  are 
  

   composed 
  of 
  joints 
  similar 
  to 
  those 
  of 
  an 
  ordinary 
  crinoidal 
  

   column, 
  and 
  vary 
  in 
  number 
  from 
  five 
  to 
  twelve 
  or 
  more, 
  

   and 
  are 
  arranged 
  symmetrically 
  with 
  respect 
  to 
  two 
  axes 
  

   at 
  right 
  angles 
  ; 
  they 
  bifurcate 
  at 
  the 
  third 
  or 
  fourth 
  seg- 
  

   ment 
  from 
  their 
  origin, 
  and 
  enclose 
  ambulacral 
  openings 
  

   which 
  penetrate 
  into 
  the 
  interior 
  cavities 
  of 
  the 
  body. 
  

  

  The 
  external 
  wall 
  of 
  the 
  dome 
  is 
  composed 
  of 
  two 
  distinct 
  

   layers, 
  of 
  which 
  the 
  infolding 
  and 
  extension 
  of 
  the 
  inner 
  one 
  

   forms 
  the 
  partitions 
  dividing 
  the 
  chambers. 
  No 
  traces 
  of 
  free 
  

   arms 
  have 
  been 
  observed. 
  Column 
  cylindrical, 
  smooth 
  near 
  the 
  

   body; 
  the 
  segments 
  regular. 
  The 
  interior 
  canal 
  is 
  five-lobed, 
  

   and 
  is 
  divided 
  and 
  continued 
  through 
  the 
  basal 
  rays 
  and 
  

   their 
  ramifications; 
  not 
  opening 
  into 
  any 
  interior 
  cavity 
  of 
  

   the 
  body, 
  so 
  far 
  as 
  observed. 
  

  

  This 
  remarkable 
  crinoidal 
  body 
  is 
  so 
  totally 
  unlike 
  any 
  

   previously 
  described 
  form, 
  within 
  my 
  knowledge, 
  that 
  its 
  true 
  

   characters 
  and 
  relations 
  are 
  not 
  at 
  once 
  evident. 
  There 
  

   is 
  no 
  doubt 
  as 
  to 
  its 
  crinoidal 
  nature, 
  but 
  there 
  is 
  no 
  apparent 
  

   analogy 
  of 
  its 
  parts 
  with 
  ordinary 
  crinoids. 
  Some 
  of 
  its 
  char- 
  

   acters 
  would 
  indicate 
  that 
  it 
  is 
  a 
  curiously 
  modified 
  and 
  en- 
  

   larged 
  summit 
  or 
  dome 
  ; 
  that 
  the 
  visceral 
  cavity 
  is 
  a 
  small 
  

   internal 
  chamber 
  immediately 
  over 
  the 
  column-attachment 
  ; 
  

   and 
  that 
  the 
  lobes 
  are 
  an 
  abnormal 
  development 
  of 
  the 
  inter- 
  

   brachial 
  or 
  interradial 
  spaces. 
  But 
  the 
  more 
  probable 
  theory 
  

   in 
  regard 
  to 
  this 
  fossil, 
  points 
  to 
  afunctional 
  similarity 
  with 
  a 
  

   crinoidal 
  root, 
  as 
  in 
  Ancyrocrinus 
  from 
  the 
  upper 
  Helderberg 
  

   and 
  Hamilton 
  groups, 
  in 
  which 
  there 
  is 
  a 
  bulbous 
  growth 
  at 
  

   one 
  extremity 
  of 
  the 
  column, 
  supposed 
  to 
  act 
  as 
  a 
  float 
  or 
  an- 
  

   chor 
  to 
  the 
  body 
  and 
  arms. 
  Viewing 
  it 
  in 
  this 
  respect, 
  it 
  may 
  

   be 
  regarded 
  as 
  a 
  large 
  chambered 
  bulb, 
  with 
  an 
  attached 
  col- 
  

   umn, 
  on 
  the 
  distal 
  extremity 
  of 
  which 
  was 
  a 
  calyx, 
  having 
  

   characters 
  unknown 
  at 
  the 
  present 
  time. 
  In 
  this 
  aspect, 
  it 
  

   must 
  have 
  been 
  a 
  free 
  floating 
  organism, 
  similar 
  in 
  its 
  habits 
  

   to 
  the 
  recent 
  Medusce 
  and 
  Comatulce. 
  The 
  lack 
  of 
  definition 
  

   and 
  symmetry 
  which 
  these 
  crinoidal 
  bodies 
  assume 
  would 
  be 
  

   an 
  argument 
  in 
  support 
  of 
  this 
  view, 
  and 
  find 
  an 
  explanation 
  

   in 
  their 
  consequent 
  secondary 
  functional 
  importance, 
  and 
  sep- 
  

   aration 
  from 
  the 
  governing 
  center 
  or 
  centers. 
  

  

  