﻿art 
  9 
  UNUSUAL 
  FORMS 
  OF 
  FOSSIL 
  CRINOIDS 
  SPRINGER 
  9 
  

  

  numerous, 
  flat, 
  and 
  closely 
  apposed; 
  regularly 
  paired, 
  one 
  at 
  each 
  

   side 
  of 
  successive 
  columnals 
  along 
  greater 
  part 
  of 
  stem. 
  

  

  This 
  is 
  one 
  of 
  two 
  thoroughly 
  distinct 
  and 
  well 
  marked 
  forms, 
  

   both 
  described 
  by 
  Hall 
  when 
  proposing 
  the 
  genus, 
  and 
  illustrated 
  by 
  

   good 
  figures. 
  It 
  is 
  the 
  most 
  widely 
  distributed 
  species, 
  and 
  the 
  

   farthest 
  ranging. 
  Bather 
  has 
  described 
  a 
  specimen 
  of 
  it 
  from 
  the 
  

   Wenlockian 
  of 
  Gotland; 
  and 
  in 
  America 
  specimens 
  which 
  can 
  not 
  

   be 
  distinguished 
  from 
  it 
  in 
  the 
  condition 
  as 
  found 
  occur 
  in 
  nearly 
  all 
  

   the 
  formations 
  from 
  the 
  later 
  Clinton 
  through 
  the 
  greater 
  part 
  of 
  

   the 
  Niagaran. 
  Its 
  range 
  may 
  thus 
  be 
  said 
  to 
  be 
  almost 
  coextensive 
  

   with 
  the 
  principal 
  Silurian 
  formations 
  of 
  Europe 
  and 
  America. 
  

  

  Hall's 
  type 
  of 
  the 
  species 
  was 
  from 
  the 
  Rochester 
  shale 
  at 
  Lock- 
  

   port, 
  New 
  York. 
  It 
  is 
  rather 
  rare 
  at 
  that 
  locality, 
  only 
  four 
  speci- 
  

   mens 
  having 
  been 
  recognized 
  in 
  the 
  abundant 
  material 
  I 
  have 
  from 
  

   the 
  shales, 
  and 
  one 
  from 
  the 
  underlying 
  limestone 
  of 
  late 
  Clinton 
  

   age. 
  It 
  has 
  since 
  been 
  found 
  to 
  occur 
  (or 
  two 
  forms 
  indistinguishable 
  

   from 
  it 
  with 
  our 
  present 
  knowledge) 
  in 
  the 
  Brassfield 
  formation 
  of 
  

   the 
  upper 
  Clinton 
  in 
  Ohio; 
  the 
  Laurel 
  limestone 
  of 
  Indiana; 
  the 
  

   Racine 
  dolomite 
  of 
  the 
  Chicago 
  area 
  ; 
  and 
  in 
  a 
  closely 
  allied 
  species 
  

   in 
  the 
  Brownsport 
  limestone 
  of 
  the 
  later 
  Niagaran. 
  

  

  I 
  am 
  now 
  able 
  to 
  illustrate 
  the 
  species 
  more 
  fully 
  than 
  was 
  done 
  

   originally, 
  showing 
  the 
  extent 
  of 
  the 
  column 
  distally, 
  the 
  distribu- 
  

   tion 
  of 
  the 
  cirri 
  along 
  the 
  greater 
  part 
  of 
  its 
  length, 
  and 
  some 
  of 
  

   the 
  slender, 
  circular 
  part 
  leading 
  to 
  the 
  calyx, 
  of 
  which 
  we 
  have 
  

   the 
  crown 
  partly 
  visible 
  in 
  one 
  specimen, 
  but 
  not 
  enough 
  to 
  deter- 
  

   mine 
  its 
  structure. 
  As 
  shown 
  by 
  these 
  specimens, 
  the 
  stem 
  beyond 
  

   the 
  close 
  coil 
  is 
  quite 
  long, 
  and 
  the 
  cirri 
  very 
  narrow, 
  flat 
  and 
  closely 
  

   packed, 
  so 
  that 
  as 
  seen 
  from 
  either 
  side 
  each 
  columnal 
  bears 
  a 
  cirrus. 
  

   In 
  the 
  large 
  specimen 
  (pi. 
  1, 
  fig. 
  1) 
  the 
  stem 
  extends 
  for 
  12 
  cm. 
  

   beyond 
  the 
  close 
  coil, 
  in 
  which 
  it 
  is 
  4 
  mm. 
  wide, 
  maintaining 
  this 
  

   width 
  to 
  the 
  incomplete 
  distal 
  end. 
  In 
  the 
  St. 
  Paul 
  specimen 
  (pi. 
  

   1, 
  fig. 
  7) 
  the 
  stem 
  is 
  broken 
  off 
  where 
  it 
  was 
  beginning 
  to 
  open 
  a 
  

   short 
  distance 
  beyond 
  the 
  close 
  coil, 
  and 
  it 
  is 
  of 
  the 
  full 
  width 
  of 
  

   4 
  mm., 
  which 
  is 
  probably 
  maintained 
  for 
  a 
  distance 
  of 
  at 
  least 
  7 
  cm. 
  

   more. 
  There 
  are 
  five 
  other 
  specimens 
  from 
  the 
  St. 
  Paul 
  locality, 
  

   more 
  or 
  less 
  fragmentary, 
  and 
  in 
  all 
  but 
  one 
  of 
  them 
  the 
  convolutus 
  

   plan 
  of 
  cirri 
  is 
  constant. 
  

  

  The 
  occurrence 
  of 
  this 
  species 
  in 
  the 
  Laurel 
  limestone 
  at 
  St. 
  Paul, 
  

   Indiana, 
  is 
  an 
  excellent 
  illustration 
  of 
  Foerste's 
  observation 
  6 
  that 
  

   "students 
  of 
  the 
  crinoidea 
  are 
  aware 
  of 
  the 
  frequency 
  with 
  which 
  

   species 
  occurring 
  at 
  St. 
  Paul 
  find 
  their 
  nearest 
  relatives 
  in 
  the 
  Wal- 
  

   dron, 
  Brownsport, 
  and 
  Racine, 
  many 
  of 
  them 
  showing 
  Gotlandian 
  

   affinities." 
  

  

  Ohio 
  Jouru. 
  Sci., 
  vol. 
  21, 
  Dec. 
  1920, 
  p. 
  64. 
  

   23832—26 
  2 
  

  

  