﻿252 
  Mr. 
  F. 
  A. 
  Blither 
  on 
  

  

  latter 
  ; 
  and 
  tliis 
  carries 
  with 
  it> 
  first 
  the 
  boundinof 
  of 
  the 
  

   peripi'oct 
  by 
  tliat 
  radial, 
  instead 
  of 
  by 
  a 
  reduced 
  right 
  

   posterior 
  radial 
  and 
  the 
  adjoining 
  right 
  anterior 
  radial 
  ; 
  

   secondly 
  the 
  position 
  of 
  the 
  periproct 
  in 
  the 
  middle 
  line 
  of 
  

   the 
  posterior 
  basal, 
  instead 
  of 
  at 
  the 
  adjacent 
  upper 
  corners 
  

   of 
  the 
  posterior 
  aud 
  right 
  posterior 
  basals. 
  

  

  Tliere 
  are, 
  however, 
  distinct 
  moditications 
  from 
  a 
  normally 
  

   symmetrical 
  crinoid. 
  The 
  whole 
  cup 
  is 
  raised 
  along 
  the 
  left 
  

   posterior 
  radius, 
  and 
  depressed 
  tov^ards 
  the 
  opposite 
  sule, 
  

   aud 
  this 
  position 
  was 
  accentuated 
  by 
  the 
  slope 
  of 
  the 
  stem- 
  

   facet. 
  The 
  asymmetry 
  of 
  the 
  radial 
  region 
  is 
  shown 
  in 
  

   Austin's 
  reconstruction 
  (PI. 
  X. 
  fig. 
  2<?), 
  but 
  the 
  slope 
  of 
  

   the 
  stem-facet 
  is 
  not 
  shown 
  and 
  would 
  be 
  inconsistent 
  with 
  

   such 
  a 
  stem 
  and 
  general 
  habitus 
  as 
  are 
  represented 
  in 
  that 
  

   drawing. 
  

  

  Further, 
  there 
  seems 
  good 
  reason 
  to 
  suppose 
  that 
  the 
  arm 
  

   borne 
  by 
  the 
  left 
  posterior 
  radial 
  was 
  relatively 
  stout, 
  but 
  

   that 
  the 
  other 
  arms 
  were 
  much 
  reduced, 
  and 
  possibly 
  

   modified 
  into 
  flattened 
  plates 
  serving 
  more 
  for 
  protection 
  of 
  

   tiie 
  peristome 
  than 
  for 
  the 
  collection 
  of 
  food 
  (PI. 
  X. 
  

   fig. 
  !</). 
  Austin's 
  reconstruction 
  is 
  certainly 
  incorrect 
  in 
  

   showing 
  five 
  small 
  arms 
  of 
  equal 
  size. 
  

  

  The 
  general 
  slnipe 
  of 
  the 
  i)osterior 
  basal 
  is 
  like 
  that 
  in 
  

   Ci/donocrimis 
  (Ann. 
  & 
  Mag. 
  IS 
  at. 
  Hist., 
  Nov. 
  1913, 
  p^ 
  388), 
  

   but 
  the 
  periproct 
  was 
  deHnitely 
  closed 
  above 
  by 
  the 
  union 
  of 
  

   the 
  riidials, 
  with 
  or 
  without 
  a 
  small 
  intercalated 
  plate. 
  There 
  

   is 
  no 
  reason 
  to 
  doubt 
  the 
  correctness 
  of 
  Austin^s 
  representation 
  

   of 
  a 
  small 
  anal 
  tube 
  projecting 
  outwards 
  from 
  the 
  periproct 
  

   (PI. 
  X. 
  Hg. 
  2 
  b). 
  

  

  In 
  all 
  these 
  modified 
  features, 
  Si/cocrimis 
  anapeptamenus 
  is 
  

   much 
  nearer 
  to 
  "' 
  Hypocrinus" 
  pirifor/iiis 
  than 
  to 
  such 
  a 
  

   form 
  as 
  Cydunucrvius, 
  and 
  it 
  may 
  indeed 
  be 
  questioned 
  

   whether 
  the 
  two 
  species 
  should 
  be 
  separated 
  generically. 
  

   Apart 
  from 
  difference 
  of 
  size, 
  the 
  only 
  distinction 
  lies 
  in 
  the 
  

   slight 
  intensification 
  of 
  all 
  the 
  above-mentioned 
  features 
  in 
  

   " 
  //." 
  piriformis. 
  

  

  The 
  Systematic 
  Conclusions 
  to 
  which 
  we 
  are 
  led 
  seem 
  to 
  be 
  

   these, 
  iiycocrii.ns 
  was 
  described 
  by 
  the 
  Austins 
  in 
  terms 
  

   that 
  were 
  intelligible 
  enough 
  to 
  contemporary 
  writers, 
  as 
  

   proved 
  by 
  the 
  remarks 
  of 
  Von 
  Buch. 
  Our 
  analysis 
  of 
  their 
  

   definitions 
  has, 
  however, 
  brought 
  out 
  rather 
  more 
  clearly 
  

   the 
  fact 
  that 
  at 
  least 
  two 
  quite 
  distinct 
  plans 
  of 
  structure 
  — 
  

   the 
  monocyclic 
  and 
  the 
  dicyclic 
  base 
  — 
  were 
  confused 
  by 
  

   them. 
  The 
  dicyclic 
  j)lan 
  seems 
  to 
  be 
  that 
  most 
  in 
  accord 
  

   with 
  the 
  intention 
  of 
  the 
  generic 
  diagnosiSj 
  aud 
  we 
  may 
  

  

  