﻿art 
  9 
  UNUSUAL 
  FORMS 
  OF 
  FOSSIL 
  CRINOIDS 
  SPBINGER 
  35 
  

  

  sionally, 
  as 
  an 
  independent 
  modification, 
  and 
  in 
  otherwise 
  unrelated 
  

   forms; 
  specifically 
  distinct, 
  and 
  sufficiently 
  rare 
  to 
  fall 
  within 
  our 
  

   category 
  of 
  " 
  unusual 
  forms." 
  It 
  is 
  not 
  even 
  a 
  generic 
  character. 
  

  

  Hitherto 
  the 
  recumbent 
  type 
  of 
  arms 
  has 
  been 
  observed 
  among 
  the 
  

   following 
  families 
  and 
  genera 
  of 
  the 
  Camerata 
  : 
  

  

  Family 
  Rhodocrinidae, 
  genus 
  Gilbertsocrinus. 
  

  

  Family 
  Batocrinidae, 
  genus 
  Barirandeocrinus. 
  

  

  Family 
  Platycrinidae, 
  genus 
  Eucladocrinus. 
  

  

  Family 
  Hexacrinidae, 
  genus 
  Dichocrinus. 
  

  

  Family 
  Hexacrinidae, 
  genus 
  Acroarinus. 
  

  

  I 
  have 
  now 
  to 
  add 
  a 
  remarkable 
  new 
  species 
  of 
  Macrostylocrinus 
  

   among 
  the 
  Melocrinidae, 
  and 
  another 
  of 
  the 
  typical 
  Platycrinus. 
  

  

  The 
  oldest 
  example 
  now 
  known, 
  and 
  one 
  of 
  the 
  most 
  characteristic, 
  

   of 
  this 
  type 
  of 
  arms 
  is 
  Barrandeocrinus 
  from 
  the 
  Silurian 
  of 
  the 
  

   island 
  of 
  Gotland 
  — 
  a 
  form 
  with 
  the 
  calyx 
  of 
  the 
  Batocrinidae. 
  It 
  

   exhibits 
  the 
  extreme 
  compactness 
  of 
  the 
  curtain 
  of 
  arms 
  as 
  they 
  press 
  

   firmly 
  against 
  the 
  calyx 
  and 
  stem, 
  leaving 
  distinct 
  impressions 
  due 
  

   to 
  the 
  protracted 
  pressure, 
  as 
  is 
  shown 
  by 
  the 
  beautiful 
  figure 
  drawn 
  

   by 
  Mr. 
  Liljevall 
  from 
  one 
  of 
  the 
  specimens 
  in 
  the 
  Stockholm 
  Museum, 
  

   published 
  by 
  Wachsmuth 
  and 
  Springer 
  in 
  the 
  North 
  American 
  

   Crinoidea 
  Camerata 
  (pi. 
  8, 
  fig. 
  1), 
  and 
  reproduced 
  herein, 
  as 
  plate 
  9, 
  

   figure 
  6, 
  and 
  by 
  another 
  from 
  a 
  specimen 
  of 
  my 
  own, 
  figure 
  7, 
  

   showing 
  the 
  calyx 
  completely 
  enveloped 
  by 
  the 
  arms. 
  

  

  The 
  next 
  in 
  order 
  was 
  a 
  holdover 
  from 
  the 
  Silurian, 
  which 
  did 
  not 
  

   take 
  on 
  the 
  recumbent 
  arm 
  structure 
  until 
  it 
  reappeared 
  under 
  a 
  new 
  

   species 
  in 
  the 
  Devonian, 
  which 
  will 
  now 
  be 
  described. 
  

  

  Genus 
  MACROSTYLOCRINUS 
  Hall 
  

  

  Macrostylocrinus 
  Hall, 
  Pal. 
  New 
  York, 
  vol. 
  2, 
  1852, 
  p. 
  203. 
  

   Silurian 
  to 
  Devonian. 
  

  

  MACROSTYLOCRINUS 
  RECUMBENS, 
  new 
  species 
  

  

  Plate 
  9, 
  figs. 
  1-4 
  

  

  The 
  genus 
  Macrostylocrinus 
  Hall, 
  of 
  the 
  family 
  Melocrinidae, 
  is 
  

   diagnosed 
  by 
  Wachsmuth 
  and 
  Springer 
  16 
  substantially 
  as 
  follows 
  : 
  

  

  Monocyclic. 
  Lower 
  brachials, 
  with 
  well 
  defined 
  interbrachials 
  between 
  them, 
  

   forming 
  a 
  part 
  of 
  the 
  dorsal 
  cup. 
  Radials 
  in 
  contact 
  all 
  around. 
  Basals 
  

   three, 
  unequal. 
  Interbrachials 
  few. 
  Anal 
  area 
  much 
  the 
  widest, 
  and 
  quite 
  

   distinct; 
  three 
  plates 
  in 
  the 
  first 
  range, 
  the 
  middle 
  one 
  large, 
  supported 
  by 
  

   the 
  sloping 
  shoulders 
  of 
  the 
  two 
  posterior 
  radials, 
  and 
  flanked 
  by 
  a 
  smaller 
  

   one 
  at 
  either 
  side 
  which, 
  together 
  with 
  the 
  first 
  primibrach, 
  rests 
  upon 
  the 
  

   upper 
  face 
  of 
  the 
  radial 
  ; 
  the 
  middle 
  or 
  anal 
  plate 
  is 
  usually 
  followed 
  by 
  one 
  

   or 
  two 
  other 
  anals, 
  longitudinally 
  arranged. 
  Radials 
  very 
  large, 
  their 
  upper 
  

  

  1,1 
  North 
  American 
  Crinoidea 
  Camerata, 
  1897, 
  p. 
  28H. 
  

  

  