﻿Lower 
  Helderberg 
  Cristoidea. 
  207 
  

  

  Camaeoceinus 
  stellatus 
  n. 
  sp. 
  

  

  Plate 
  35, 
  figs. 
  1-8. 
  

  

  Body 
  oblate-spheroidal, 
  convex 
  above, 
  flattened 
  or 
  some- 
  

   what 
  concave 
  below, 
  with 
  from 
  three 
  to 
  twelve 
  low, 
  rounded 
  

   lobes 
  on 
  the 
  basal 
  margin. 
  

  

  The 
  base 
  is 
  composed 
  of 
  spreading 
  radiciform, 
  bifurcating 
  

   branches, 
  connected 
  by 
  a 
  stellate 
  network 
  of 
  liner 
  ramifica- 
  

   tions, 
  forming 
  the 
  plates 
  of 
  the 
  base 
  ; 
  the 
  whole 
  being 
  sur- 
  

   rounded 
  by 
  an 
  irregular 
  projected 
  margin, 
  and 
  occupying 
  an 
  

   area 
  having 
  a 
  diameter 
  equal 
  to 
  from 
  one-half 
  to 
  two-thirds 
  

   the 
  transverse 
  diameter 
  of 
  the 
  body. 
  The 
  basal 
  branches, 
  of 
  

   which 
  there 
  are 
  usually 
  about 
  eight, 
  bifurcate 
  at 
  the 
  third 
  

   segment 
  from 
  their 
  origin, 
  and 
  surround 
  large 
  ambulacra! 
  

   openings 
  into 
  the 
  interior 
  cavities 
  of 
  the 
  body. 
  The 
  section 
  

   represented 
  in 
  fig. 
  5, 
  pi. 
  35, 
  shows 
  some 
  evidences 
  of 
  a 
  coni- 
  

   cal 
  cavity 
  above 
  the 
  center 
  of 
  the 
  base, 
  and 
  a 
  large 
  horizontal 
  

   septum, 
  extending 
  parallel 
  to 
  the 
  base 
  and 
  at 
  a 
  distance 
  above 
  

   it, 
  equal 
  to 
  the 
  height 
  of 
  the 
  internal 
  conical 
  chamber; 
  but 
  this 
  

   does 
  not 
  appear 
  to 
  be 
  a 
  constant 
  character. 
  

  

  The 
  body 
  is 
  divided 
  into 
  four 
  or 
  more 
  large 
  chambers, 
  or 
  

   compartments, 
  by 
  radiating 
  partitions 
  from 
  a 
  central 
  vertical 
  

   axis. 
  Near 
  the 
  summit, 
  at 
  the 
  base 
  and 
  along 
  the 
  sides, 
  

   there 
  are 
  frequently 
  several 
  accessory 
  chambers 
  formed 
  by 
  a 
  

   division 
  and 
  divergence 
  of 
  the 
  primary 
  septa. 
  

  

  The 
  external 
  wall 
  of 
  the 
  lateral 
  and 
  upper 
  portions 
  is 
  com- 
  

   posed 
  of 
  two 
  layers 
  of 
  large 
  and 
  small 
  stellate 
  plates, 
  con- 
  

   nected 
  by 
  numerous 
  processes. 
  Each 
  star 
  is 
  marked 
  

   by 
  a 
  central 
  rounded 
  node, 
  and 
  the 
  rays 
  vary 
  in 
  number 
  from 
  

   three 
  to 
  ten. 
  Column 
  smooth, 
  round 
  near 
  its 
  attachment. 
  

  

  The 
  largest 
  specimen 
  of 
  this 
  species 
  observed, 
  has 
  a 
  trans- 
  

   verse 
  diameter 
  of 
  110 
  mm. 
  with 
  a 
  vertical 
  diameter 
  of 
  nearly 
  

   60 
  mm. 
  The 
  basal 
  branches 
  of 
  the 
  same 
  specimen 
  occupy 
  an 
  

   area 
  having 
  a 
  diameter 
  of 
  50 
  mm., 
  or 
  nearly 
  one-half 
  the 
  trans- 
  

   verse 
  diameter 
  of 
  the 
  body. 
  In 
  a 
  smaller 
  specimen 
  whose 
  

   transverse 
  diameter 
  is 
  55 
  mm. 
  the 
  basal 
  area 
  measures 
  28 
  mm., 
  

   or 
  nearly 
  the 
  same 
  proportions 
  as 
  in 
  the 
  larger 
  specimen. 
  

  

  This 
  species 
  is 
  distinguished 
  from 
  C. 
  Saffordi 
  by 
  its 
  more 
  

   depressed 
  form, 
  comparatively 
  larger 
  basal 
  area, 
  more 
  numer- 
  

   ous 
  ambulacra, 
  and 
  in 
  the 
  stellate 
  structure 
  of 
  the 
  external 
  

   walls. 
  Tn 
  some 
  of 
  its 
  features 
  it 
  more 
  nearly 
  resembles 
  C. 
  

   Clarkii, 
  but 
  the 
  unsymmetrical 
  form 
  of 
  that 
  species, 
  the 
  

  

  