﻿UNUSUAL 
  FORMS 
  OF 
  FOSSIL 
  CRINOIDS 
  

  

  By 
  Frank 
  Springer, 
  

  

  Associate 
  in 
  Paleontology, 
  United 
  States 
  National 
  Museum 
  

  

  INTRODUCTION 
  

  

  It 
  was 
  originally 
  my 
  intention 
  when 
  preparing 
  the 
  monograph 
  on 
  

   the 
  Crinoidea 
  Flexibilia 
  to 
  follow 
  it 
  up 
  with 
  a 
  similar 
  systematic 
  

   treatise 
  on 
  the 
  Inadunata. 
  But 
  the 
  time 
  and 
  labor 
  consumed 
  in 
  

   bringing 
  out 
  such 
  works 
  proved 
  to 
  be 
  too 
  great, 
  and 
  I 
  have 
  been 
  

   compelled 
  to 
  relinquish 
  the 
  project 
  for 
  the 
  last-mentioned 
  treatise. 
  

   Many 
  preparatory 
  studies 
  were 
  made, 
  however, 
  with 
  such 
  a 
  work 
  in 
  

   view, 
  some 
  of 
  which 
  are 
  embraced 
  in 
  the 
  present 
  paper, 
  containing 
  

   the 
  results 
  of 
  researches 
  extending 
  over 
  many 
  years, 
  which 
  I 
  have 
  

   long 
  desired 
  to 
  publish, 
  but 
  which 
  have 
  been 
  delayed 
  by 
  the 
  pressure 
  

   of 
  other 
  matters. 
  The 
  material 
  used 
  is 
  chiefly 
  from 
  my 
  own 
  col- 
  

   lection, 
  now 
  in 
  the 
  United 
  States 
  National 
  Museum, 
  much 
  of 
  it 
  

   accumulated 
  with 
  special 
  reference 
  to 
  these 
  researches. 
  Most 
  of 
  the 
  

   drawings 
  have 
  been 
  made 
  by 
  Mr. 
  Kenneth 
  M. 
  Chapman, 
  of 
  Santa 
  

   Fe, 
  New 
  Mexico, 
  and 
  some 
  by 
  Miss 
  Francesca 
  Wieser, 
  of 
  the 
  Na- 
  

   tional 
  Museum. 
  I 
  am 
  much 
  indebted 
  to 
  Dr. 
  R. 
  S. 
  Bassler 
  and 
  Dr. 
  

   C. 
  E. 
  Resser, 
  of 
  the 
  National 
  Museum, 
  for 
  their 
  assistance 
  in 
  making 
  

   the 
  photographs 
  upon 
  which 
  the 
  drawings 
  are 
  based. 
  

  

  THE 
  USUAL 
  STRUCTURE 
  OF 
  CRINOIDS 
  

  

  The 
  generalized 
  picture 
  of 
  a 
  crinoid, 
  as 
  seen 
  in 
  the 
  forms 
  by 
  

   which 
  the 
  class 
  is 
  most 
  commonly 
  known, 
  is 
  that 
  of 
  a 
  marine 
  organ- 
  

   ism 
  having 
  a 
  calyx, 
  cup, 
  or 
  theca 
  composed 
  of 
  calcareous 
  plates 
  defi- 
  

   nitely 
  arranged, 
  inclosing 
  a 
  cavity 
  which 
  contains 
  the 
  visceral 
  

   organs; 
  attached 
  to 
  the 
  sea 
  bottom 
  or 
  other 
  objects, 
  temporarily 
  or 
  

   permanently, 
  by 
  a 
  columnar 
  stem 
  formed 
  by 
  a 
  series 
  of 
  centrally 
  

   perforated 
  segments; 
  and 
  fringed 
  at 
  the 
  opposite 
  end 
  by 
  a 
  ring 
  of 
  

   movable, 
  food-gathering 
  appendages 
  called 
  arms; 
  these 
  are 
  likewise 
  

   built 
  up 
  of 
  calcareous 
  segments, 
  but 
  instead 
  of 
  being 
  pierced 
  by 
  a 
  

   central 
  opening 
  for 
  a 
  tubular 
  canal, 
  as 
  in 
  the 
  stem, 
  they 
  are 
  notched 
  

   at 
  one 
  side, 
  forming 
  a 
  groove 
  along 
  which 
  the 
  microscopic 
  food 
  is 
  

  

  No. 
  2581.— 
  Proceedings 
  U. 
  S. 
  National 
  Museum, 
  Vol. 
  67. 
  Art. 
  9. 
  

  

  23832—26 
  1 
  

  

  