﻿40 
  P. 
  H. 
  CARPENTER 
  ON 
  SOME 
  NEW 
  OR 
  

  

  2. 
  Antedon 
  calloviensis, 
  n. 
  sp. 
  Fig. 
  2. 
  

  

  A.ctinometra 
  calloviensis, 
  P. 
  H. 
  Carpenter, 
  Abstracts 
  of 
  the 
  Pro- 
  

   ceedings 
  Geol. 
  Soc. 
  no. 
  407, 
  June 
  22, 
  1881, 
  p. 
  98. 
  

  

  The 
  centrodorsal 
  is 
  low 
  and 
  basin-shaped, 
  slightly 
  produced 
  at 
  

   the 
  interradial 
  angles, 
  and 
  nearly 
  covered 
  by 
  about 
  30 
  cirrhus- 
  

   sockets. 
  The 
  lowest 
  joint 
  of 
  one 
  (probably 
  mature) 
  cirrhus 
  is 
  still 
  

   attached 
  to 
  its 
  socket, 
  and 
  close 
  to 
  it 
  is 
  the 
  basal 
  portion 
  of 
  another, 
  

   but 
  much 
  younger 
  one. 
  The 
  first 
  radials 
  are 
  partially 
  visible 
  all 
  

   round 
  the 
  edge 
  of 
  the 
  centrodorsal, 
  from 
  which 
  they 
  are 
  separated 
  

   at 
  the 
  interradial 
  angles 
  of 
  the 
  calyx 
  by 
  the 
  small 
  basals 
  ; 
  their 
  

   line 
  of 
  junction 
  with 
  the 
  second 
  radials 
  is 
  rather 
  incurved, 
  though 
  

   less 
  so 
  than 
  in 
  the 
  preceding 
  species. 
  The 
  second 
  radials 
  are 
  very 
  

   convex, 
  and 
  widely 
  hexagonal, 
  being 
  only 
  united 
  to 
  their 
  fellows 
  by 
  

   less 
  than 
  half 
  their 
  length. 
  The 
  axillaries 
  are 
  wide 
  and 
  penta- 
  

   gonal, 
  and 
  less 
  than 
  twice 
  the 
  length 
  of 
  the 
  second 
  radials, 
  their 
  

  

  Fig. 
  2. 
  — 
  Antedon 
  calloviensis, 
  n. 
  sp. 
  

  

  

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

   From 
  the 
  Kelloway 
  rock 
  of 
  Sutton 
  Benger. 
  

  

  proportions 
  being 
  length 
  : 
  width 
  = 
  10 
  : 
  17. 
  The 
  first 
  brachials 
  are 
  

   united 
  in 
  pairs 
  for 
  about 
  half 
  their 
  length 
  by 
  their 
  inner 
  ends, 
  and 
  

   their 
  terminal 
  edges 
  are 
  nearly 
  parallel 
  ; 
  while 
  the 
  second 
  are 
  some- 
  

   what 
  more 
  wedge-shaped, 
  their 
  inner 
  sides 
  being 
  considerably 
  shorter 
  

   than 
  the 
  outer 
  ones. 
  The 
  oblong 
  third 
  brachial 
  is 
  usually 
  a 
  syzygial 
  

   or 
  double 
  joint, 
  one 
  out 
  of 
  the 
  five 
  which 
  remain 
  being 
  an 
  exception 
  

   to 
  this 
  rule. 
  The 
  first 
  joints 
  of 
  the 
  pinnules 
  on 
  the 
  second 
  brachials 
  

   are 
  visible 
  at 
  the 
  bases 
  of 
  one 
  or 
  two 
  arms. 
  

  

  Size. 
  Diameter 
  of 
  centrodorsal 
  6 
  mm. 
  ; 
  diameter 
  across 
  the 
  circle 
  

   of 
  radial 
  axillaries 
  11-5 
  mm. 
  

  

  Horizon 
  and 
  locality. 
  The 
  Kelloway 
  Kock 
  of 
  Sutton 
  Benger. 
  

  

  Remarks. 
  These 
  two 
  species, 
  occurring 
  at 
  different 
  horizons, 
  are 
  

   very 
  closely 
  allied. 
  Ant. 
  calloviensis 
  has 
  fewer 
  cirrhi 
  and 
  a 
  less 
  

   spreading 
  centrodorsal, 
  so 
  that 
  the 
  first 
  radials 
  are 
  visible 
  all 
  round, 
  

   and 
  not 
  more 
  or 
  less 
  completely 
  concealed 
  as 
  is 
  the 
  case 
  with 
  some 
  

   of 
  those 
  of 
  Ant. 
  latiradia. 
  The 
  second 
  radials, 
  too, 
  have 
  their 
  

   proximal 
  ends 
  less 
  closely 
  united 
  than 
  in 
  Ant. 
  latiradia. 
  The 
  

  

  