﻿NOTICE 
  OF 
  SOME 
  REMARKABLE 
  CRINOIDAL 
  FORMS 
  

  

  FROM 
  THE 
  LOWER 
  HELDERBERG 
  GROUP. 
  

  

  By 
  JAMES 
  HALL 
  

  

  In 
  addition 
  to 
  several 
  aberrant 
  forms 
  of 
  Crinoidea, 
  for 
  

   which 
  genera 
  have 
  been 
  constituted, 
  the 
  species 
  here 
  noticed 
  

   furnish 
  some 
  information 
  as 
  to 
  the 
  extreme 
  variations 
  

   which 
  these 
  organisms 
  can 
  assume 
  in 
  their 
  mode 
  of 
  life 
  T 
  and 
  

   in 
  the 
  special 
  modifications 
  of 
  parts 
  of 
  their 
  organism. 
  The 
  

   genera 
  Edriocrinus, 
  Ancyrocrinus 
  and 
  Lichenocrinus, 
  

   depart 
  in 
  their 
  habits, 
  and 
  in 
  some 
  degree 
  in 
  their 
  structure, 
  

   from 
  the 
  ordinary 
  forms 
  of 
  the 
  group, 
  but 
  with, 
  the 
  exception 
  

   of 
  Ancyrocrinus, 
  they 
  bear 
  slight 
  relation 
  to 
  the 
  species 
  of 
  

   the 
  present 
  paper. 
  

  

  The 
  specimens 
  from 
  the 
  Tentaculite 
  limestone 
  in 
  Schoharie, 
  

   N. 
  Y., 
  were 
  purchased 
  with 
  the 
  Gfebhard 
  collection 
  in 
  1872, 
  

   and 
  have 
  remained 
  unpublished 
  in 
  the 
  hope 
  of 
  arriving 
  at 
  a 
  

   more 
  satisfactory 
  determination 
  of 
  the 
  nature 
  of 
  this 
  remarka- 
  

   ble 
  form. 
  During 
  the 
  past 
  summer, 
  Prof. 
  James 
  M. 
  Safford, 
  of 
  

   Nashville, 
  Tennessee, 
  kindly 
  placed 
  at 
  my 
  disposal 
  numerous 
  

   specimens 
  of 
  an 
  identical 
  nature 
  from 
  the 
  same 
  horizon 
  in 
  Ten- 
  

   nessee, 
  and 
  on 
  this 
  material, 
  together 
  with 
  the 
  New 
  York 
  speci- 
  

   mens 
  in 
  the 
  State 
  Museum, 
  the 
  generic 
  characters 
  with 
  the 
  

   following 
  descriptions 
  of 
  the 
  species 
  are 
  based. 
  

  

  CAMAROCRINUS 
  nov. 
  gen. 
  

  

  Body 
  large, 
  externally 
  lobed, 
  chambered 
  within, 
  varying 
  

   from 
  transversely 
  or 
  longitudinally 
  oblate-spheroidal 
  to 
  sub- 
  

   spherical, 
  and 
  frequently 
  assuming 
  an 
  unsymmetrical 
  form 
  

   from 
  the 
  unequal 
  development 
  of 
  the 
  lobes 
  corresponding 
  

   to 
  the 
  internal 
  chambers. 
  The 
  cavity 
  of 
  the 
  body 
  or 
  dome 
  is 
  

   divided 
  into 
  two 
  or 
  more 
  large 
  compartments, 
  with 
  usually 
  

   several 
  smaller 
  accessory 
  chambers, 
  by 
  vertical 
  and 
  hori- 
  

   zontal 
  partitions 
  which 
  are 
  extensions 
  of 
  the 
  substance 
  of 
  the 
  

   inner 
  walls 
  of 
  the 
  dome. 
  

  

  The 
  basal 
  portion 
  occupies 
  a 
  subcircular 
  area, 
  which 
  is 
  

   placed 
  in 
  a 
  central 
  position 
  with 
  regard 
  to 
  the 
  disposition 
  of 
  

   the 
  lobes 
  of 
  the 
  body, 
  and 
  is 
  surrounded 
  by 
  an 
  elevated 
  pro- 
  

  

  