﻿art 
  9 
  UNUSUAL 
  FORMS 
  OF 
  FOSSIL 
  CRINOIDS 
  SPRINGER 
  25 
  

  

  that 
  the 
  prolific 
  genus 
  Hexacrinus 
  among 
  Devonian 
  crinoids 
  would 
  

   do 
  something 
  of 
  the 
  same 
  kind. 
  14 
  

  

  This 
  remarkable 
  species 
  is 
  named 
  in 
  honor 
  of 
  Prof. 
  Johannes 
  

   Wanner, 
  of 
  the 
  University 
  of 
  Bonn, 
  an 
  ardent 
  student 
  of 
  the 
  crinoids, 
  

   whose 
  works 
  upon 
  the 
  Echinoderms 
  of 
  the 
  island 
  of 
  Timor 
  have 
  

   brought 
  to 
  light 
  one 
  of 
  the 
  most 
  extraordinary 
  crinoidal 
  faunas 
  ever 
  

   discovered. 
  

  

  Horizon 
  and 
  locality.— 
  Middle 
  Devonian, 
  Eifel 
  limestone; 
  Priim, 
  

   Eifel, 
  Germany. 
  

  

  CAMPTOCRINUS 
  Wachsmuth 
  and 
  Springer 
  

  

  Plates 
  7, 
  8 
  

  

  Camptocrinus 
  Wachsmuth 
  and 
  Springer, 
  North 
  American 
  Crinoidea 
  

   Camerata, 
  1S97, 
  p. 
  779. 
  Mississippian 
  : 
  Burlington 
  to 
  Chester. 
  

  

  Camptocrinus 
  is 
  simply 
  a 
  Dichocrinus 
  with 
  a 
  coiled 
  bilateral 
  stem 
  ; 
  

   or 
  it 
  might 
  be 
  called 
  a 
  Myelodactylus 
  with 
  a 
  Camerate 
  crown. 
  It 
  

   is 
  the 
  Carboniferous 
  representative 
  of 
  the 
  type 
  under 
  consideration. 
  

   Whatever 
  may 
  have 
  been 
  the 
  origin 
  of 
  this 
  extreme 
  stem 
  modifica- 
  

   tion, 
  it 
  developed 
  independently 
  in 
  the 
  two 
  orders 
  of 
  the 
  Crinoidea, 
  

   without 
  the 
  slightest 
  evidence 
  of 
  any 
  evolutionary 
  connection 
  be- 
  

   tween 
  the 
  two 
  genera 
  in 
  which 
  it 
  appeared, 
  and 
  then 
  reappeared 
  

   after 
  the 
  long 
  time 
  interval 
  from 
  the 
  Lower 
  Devonian 
  to 
  the 
  Lower 
  

   Carboniferous. 
  

  

  The 
  genus 
  Dichocrinus 
  was 
  peculiarly 
  susceptible 
  to 
  secondary 
  

   modifications 
  upon 
  a 
  primitive 
  type, 
  and 
  underwent 
  a 
  number 
  of 
  

   striking 
  changes 
  involving 
  the 
  stem 
  and 
  arms. 
  The 
  stem 
  especially 
  

   was 
  in 
  a 
  plastic 
  condition, 
  yielding 
  a 
  variety 
  of 
  modifications 
  in 
  ad- 
  

   dition 
  to 
  that 
  of 
  the 
  bilateral, 
  coiled 
  feature, 
  which 
  were 
  not 
  cor- 
  

   related 
  with 
  any 
  material 
  changes 
  in 
  the 
  structure 
  of 
  the 
  crown. 
  

   Usually 
  the 
  stem 
  is 
  without 
  cirri 
  (pi. 
  11, 
  fig. 
  4), 
  but 
  in 
  some 
  of 
  the 
  

   later 
  forms 
  ordinary 
  cirri 
  are 
  present, 
  in 
  whorls 
  along 
  the 
  greater 
  

   part 
  of 
  the 
  stem. 
  I 
  have 
  some 
  excellent 
  specimens 
  showing 
  this. 
  In 
  

   one 
  species 
  the 
  cirri 
  are 
  developed 
  in 
  numerous 
  crowded 
  whorls, 
  

   limited 
  to 
  the 
  upper 
  part 
  of 
  the 
  stem, 
  and 
  rising 
  far 
  beyond 
  the 
  

   height 
  of 
  the 
  calyx 
  and 
  arms 
  (pi. 
  11, 
  fig. 
  7). 
  

  

  14 
  There 
  is 
  even 
  some 
  ground 
  for 
  suspecting 
  that 
  the 
  mysterious 
  Edriocrinus 
  might 
  be 
  

   an 
  offshoot 
  from- 
  the 
  Hexacrinidae. 
  The 
  calyx 
  is 
  fundamentally 
  similar 
  — 
  five 
  strong 
  

   radials, 
  with 
  a 
  large 
  anal 
  plate 
  of 
  similar 
  form 
  interposed 
  in 
  line 
  with 
  them. 
  As 
  it 
  is 
  

   now 
  known 
  to 
  be 
  a 
  monocyclic 
  crinoid 
  with 
  four 
  basals 
  (Springer, 
  Crinoidea 
  Flexibilia, 
  

   1920, 
  p. 
  443), 
  the 
  analogy 
  in 
  this 
  respect 
  also 
  is 
  not 
  so 
  very 
  remote. 
  The 
  Hexacrinidae 
  

   include 
  forms 
  with 
  two 
  and 
  with 
  three 
  basals, 
  why 
  not 
  four? 
  The 
  secondary 
  modification 
  

   of 
  the 
  base 
  by 
  way 
  of 
  fused 
  basals, 
  often 
  directly 
  fixed 
  without 
  a 
  stem, 
  thought 
  to 
  be 
  a 
  

   result 
  of 
  reef 
  life 
  in 
  shallow 
  waters, 
  reappears 
  in 
  different 
  geological 
  epochs 
  down 
  to 
  tiie 
  

   present 
  time, 
  in 
  wholly 
  unrelated 
  forms 
  ; 
  and 
  there 
  is 
  no 
  reason 
  a 
  priori 
  why 
  it 
  may 
  not 
  

   have 
  occurred 
  independently 
  in 
  the 
  Hexacrinidae. 
  

  

  