﻿LITTLE-KNOWN" 
  JUEASSIC 
  CELSTOLDS. 
  

  

  3£ 
  

  

  radials 
  have 
  a 
  corresponding 
  curve, 
  so 
  that 
  these 
  joints 
  are 
  con- 
  

   siderably 
  longer 
  in 
  the 
  middle 
  than 
  at 
  the 
  sides, 
  by 
  the 
  greater 
  part 
  

   of 
  which 
  they 
  are 
  united 
  to 
  their 
  fellows. 
  The 
  pentagonal 
  axillaries 
  

   are 
  short 
  and 
  wide, 
  barely 
  half 
  as 
  long 
  again 
  as 
  the 
  second 
  radials, 
  

  

  Fig. 
  1. 
  — 
  Antedon 
  latiradia, 
  n. 
  sp. 
  

  

  A. 
  From 
  beneath. 
  B. 
  From 
  the 
  side. 
  (Twice 
  the 
  natural 
  size.) 
  

   From 
  the 
  Great 
  Oolite 
  of 
  Bradford. 
  

  

  their 
  proportions 
  being 
  length 
  : 
  width 
  =11 
  : 
  20. 
  The 
  first 
  brachials 
  

   are 
  united 
  for 
  about 
  half 
  the 
  length 
  of 
  their 
  inner 
  sides, 
  which 
  are 
  

   shorter 
  than 
  the 
  outer 
  ones, 
  owing 
  to 
  the 
  inclination 
  of 
  the 
  proximal 
  

   and 
  distal 
  edges 
  to 
  one 
  another. 
  This 
  is 
  more 
  markedly 
  the 
  

   case 
  with 
  the 
  second 
  brachials. 
  The 
  third 
  brachial 
  is 
  a 
  syzygial 
  

   or 
  double 
  joint, 
  and 
  the 
  two 
  following 
  joints 
  are 
  transversely 
  oblong. 
  

   On 
  one 
  of 
  the 
  three 
  remaining 
  arm-bases 
  the 
  fifth 
  brachial 
  is 
  also 
  a 
  

   syzygial 
  joint. 
  

  

  The 
  articular 
  face 
  of 
  one 
  first 
  radial 
  is 
  visible. 
  It 
  is 
  roughly 
  

   trapezoidal 
  in 
  shape, 
  4 
  mm. 
  high, 
  and 
  a 
  trifle 
  wider 
  across 
  the 
  

   transverse 
  ridge, 
  which 
  rises 
  up 
  around 
  the 
  opening 
  of 
  the 
  axial 
  

   canal 
  into 
  a 
  triangular 
  articular 
  surface. 
  Beneath 
  this 
  is 
  a 
  small 
  fossa 
  

   with 
  a 
  deep 
  central 
  pit 
  for 
  the 
  insertion 
  of 
  the 
  dorsal 
  elastic 
  liga- 
  

   ment. 
  The 
  greater 
  part 
  of 
  the 
  articular 
  face 
  is 
  taken 
  up 
  by 
  the 
  

   large 
  plates 
  for 
  the 
  attachment 
  of 
  muscles 
  and 
  ligaments, 
  but 
  the 
  

   boundaries 
  of 
  their 
  respective 
  fossae 
  are 
  not 
  very 
  distinct. 
  There 
  is 
  

   a 
  shallow 
  but 
  wide 
  notch 
  between 
  the 
  two 
  muscle-plates, 
  though 
  it 
  

   is 
  not 
  clear 
  whether 
  there 
  was 
  any 
  vertical 
  ridge 
  descending 
  from 
  

   it 
  towards 
  the 
  opening 
  of 
  the 
  axial 
  canal. 
  If 
  there 
  was 
  one, 
  it 
  

   became 
  less 
  marked 
  as 
  it 
  approached 
  the 
  transverse 
  ridge 
  ; 
  for 
  on 
  

   each 
  side 
  of 
  the 
  apex 
  of 
  the 
  triangular 
  articular 
  surface 
  is 
  a 
  deepish 
  

   pit 
  which 
  marks 
  the 
  central 
  end 
  of 
  the 
  ligament-fossa. 
  These 
  two 
  

   pits 
  are 
  connected 
  by 
  a 
  shallow 
  depression 
  above 
  the 
  apex 
  of 
  the 
  

   tsiangle, 
  so 
  that 
  the 
  whole 
  has 
  somewhat 
  of 
  an 
  hourglass-shape. 
  

  

  Size. 
  Diameter 
  of 
  centrodorsal 
  7*5 
  mm. 
  ; 
  diameter 
  across 
  the 
  

   circle 
  of 
  radial 
  axillaries 
  14 
  mm. 
  

  

  Locality 
  and 
  horizon. 
  The 
  Great 
  Oolite, 
  Bradford. 
  

  

  