﻿art 
  9 
  UNUSUAL. 
  FORMS 
  OF 
  FOSSIL 
  CFvINOIDS 
  SPRINGER 
  61 
  

  

  growth 
  in 
  different 
  species. 
  Thus 
  F. 
  B. 
  Meek 
  commenting 
  in 
  1874 
  

   on 
  the 
  figures 
  of 
  Agassizocrinus 
  on 
  plate 
  21 
  of 
  volume 
  5 
  of 
  the 
  Illi- 
  

   nois 
  Reports 
  says: 
  

  

  Some 
  species, 
  such 
  as 
  those 
  represented 
  by 
  figs. 
  10 
  and 
  12, 
  may 
  even 
  have 
  re- 
  

   mained 
  attached 
  by 
  a 
  slender 
  column 
  during 
  their 
  whole 
  life. 
  40 
  

  

  The 
  further 
  obvious 
  conclusion 
  follows 
  that 
  Whitfield's 
  species 
  

   must 
  be 
  referred 
  to 
  Agassizocrinus 
  with 
  a 
  modified 
  diagnosis, 
  and 
  

   that 
  inasmuch 
  as 
  his 
  original 
  specific 
  name 
  was 
  not 
  preoccupied 
  un- 
  

   der 
  the 
  genus 
  to 
  which 
  it 
  now 
  proves 
  to 
  belong, 
  it 
  must 
  under 
  the 
  

   rules 
  of 
  nomenclature 
  be 
  noAv 
  restored, 
  and 
  the 
  species 
  written 
  

   Agassizocrinus 
  inequidactylus 
  (Whitfield). 
  

  

  I 
  have 
  reserved 
  for 
  special 
  mention 
  the 
  particular 
  specimen 
  which 
  

   led 
  me 
  to 
  the 
  present 
  investigation, 
  and 
  which 
  by 
  reason 
  of 
  its 
  excel- 
  

   lent 
  preservation 
  gives 
  us 
  the 
  most 
  striking 
  picture 
  of 
  the 
  remarkable 
  

   specialization 
  which 
  has 
  developed 
  in 
  this 
  genus. 
  It 
  was 
  acquired 
  

   with 
  the 
  collection 
  of 
  the 
  late 
  Col. 
  S. 
  S. 
  Lyon, 
  who 
  had 
  recognized 
  its 
  

   anomalous 
  structure, 
  and, 
  as 
  I 
  have 
  elsewhere 
  stated, 
  proposed 
  to 
  

   describe 
  it 
  under 
  one 
  of 
  his 
  favorite 
  hyphenated 
  names 
  as 
  Poterio- 
  

   crinus 
  brachialls-irregularis. 
  The 
  two 
  ponderous 
  antero-lateral 
  

   arms 
  are 
  almost 
  complete, 
  and 
  they 
  show 
  better 
  than 
  the 
  measure- 
  

   ments 
  of 
  radials 
  what 
  an 
  enormous 
  difference 
  in 
  size 
  there 
  is 
  between 
  

   them 
  and 
  the 
  other 
  arms 
  (pi. 
  15, 
  fig. 
  13). 
  The 
  specimen 
  has 
  the 
  

   infrabasals 
  divided, 
  and 
  a 
  column 
  facet 
  with 
  axial 
  opening; 
  and 
  it 
  

   belongs 
  beyond 
  question 
  to 
  the 
  species 
  described 
  by 
  Whitfield. 
  

  

  In 
  the 
  structure 
  of 
  the 
  anal 
  interradius 
  there 
  is 
  no 
  appreciable 
  dif- 
  

   ference 
  between 
  the 
  species 
  referred 
  to 
  Agassizocrinus 
  and 
  those 
  of 
  

   Cromyocrinus 
  and 
  Eupachycririus, 
  which 
  are 
  all 
  closely 
  associated 
  

   in 
  geological 
  position. 
  Bather 
  in 
  the 
  Lankester 
  Zoology 
  (pt. 
  3, 
  p. 
  

   103), 
  defined 
  Agassizocrinus 
  as 
  "a 
  Cromyocrinus 
  that 
  loses 
  its 
  col- 
  

   umn 
  in 
  adult 
  life, 
  while 
  IBB 
  fuse 
  to 
  a 
  solid 
  mass." 
  With 
  the 
  

   knowledge 
  furnished 
  by 
  the 
  present 
  investigation 
  we 
  are 
  able 
  to 
  

   place 
  the 
  definition 
  of 
  Agassizocrinus 
  upon 
  a 
  surer 
  basis, 
  distin- 
  

   guishing 
  it 
  from 
  the 
  other 
  two 
  genera 
  by 
  the 
  inequality 
  of 
  the 
  radii 
  

   due 
  to 
  the 
  greater 
  size 
  of 
  the 
  two 
  lateral 
  rays, 
  and 
  of 
  one 
  of 
  the 
  arms 
  

   of 
  which 
  they 
  are 
  composed, 
  and 
  perhaps 
  exceptionally 
  of 
  the 
  an- 
  

   terior 
  ray 
  also. 
  This 
  will 
  be 
  irrespective 
  of 
  the 
  presence 
  or 
  absence 
  

   of 
  a 
  stem, 
  although 
  the 
  strong 
  tendency 
  to 
  fusion 
  of 
  the 
  base 
  and 
  

   elimination 
  of 
  the 
  stem 
  is 
  recognized 
  : 
  

  

  Genus 
  AGASSIZOCRINUS 
  Owen 
  and 
  Shumard 
  

  

  Poteriorcrininae 
  with 
  calyx 
  elongate 
  to 
  pyriform. 
  Infrabasals 
  

   five, 
  with 
  facet 
  for 
  round 
  column 
  often 
  present, 
  but 
  more 
  frequently 
  

   fused 
  into 
  a 
  rounded 
  conical 
  base, 
  on 
  which 
  all 
  trace 
  of 
  column 
  is 
  

   Avanting. 
  Radials 
  unequal, 
  those 
  of 
  the 
  two 
  lateral 
  rays 
  (and 
  some- 
  

  

  40 
  Amer. 
  Journ. 
  Sci., 
  vol. 
  7, 
  p. 
  484. 
  

  

  