﻿856 
  PAL.KONTi>L()(iV 
  OF 
  ILLINOIS. 
  

  

  entrance 
  to 
  the 
  anal 
  aperture. 
  The 
  opening 
  into 
  this 
  cavity 
  is 
  1 
  

   Bomewhat 
  broadly 
  Bubtriangular, 
  and 
  there 
  is 
  a 
  passage 
  in 
  a 
  down- 
  

   ward 
  coarse, 
  which 
  i 
  atere 
  the 
  inner 
  body 
  at 
  the 
  end 
  of 
  the 
  oral 
  

   plat 
  

  

  The 
  ambulacra 
  are 
  almost 
  linear, 
  rounded 
  at 
  the 
  distal 
  end 
  ; 
  they 
  

   red 
  deeply 
  between 
  the 
  steep 
  sides, 
  the 
  side-pl 
  eting 
  the 
  

  

  sides 
  of 
  the 
  sinus 
  hut 
  air 
  rarely 
  toaohing 
  them. 
  The 
  ambulacra 
  

   connect 
  with 
  the 
  hody 
  through 
  the 
  lower 
  side 
  of 
  the 
  Um< 
  

   close 
  to 
  its 
  middle 
  line. 
  The 
  surface 
  of 
  the 
  ambulacra 
  is 
  divided 
  

   by 
  the 
  food 
  groove 
  only, 
  there 
  being 
  no 
  other 
  indented 
  lines 
  toward 
  

   the 
  sides, 
  such 
  8 
  in 
  the 
  Louisville 
  species. 
  The 
  Lai 
  

  

  is 
  entirely 
  covered 
  by 
  the 
  side 
  pieces, 
  it 
  is 
  lanceolate, 
  and 
  rests 
  

   with 
  its 
  proximal 
  end, 
  which 
  is 
  angular, 
  between 
  and 
  partly 
  upon 
  

   — 
  adjoining 
  oral 
  plates. 
  The 
  number 
  of 
  side 
  ) 
  tries 
  from 
  16 
  

  

  to 
  each 
  side 
  in 
  the 
  smallest 
  specimens 
  to 
  -1-1 
  or 
  28 
  in 
  the 
  lai 
  

   ones, 
  each 
  one 
  with 
  a 
  socket, 
  probably 
  for 
  the 
  reception 
  of 
  a 
  pin- 
  

   nule. 
  There 
  are 
  also 
  outer-side 
  pieces 
  but 
  no 
  hydros]'!! 
  

   The 
  oral 
  aperture 
  is 
  pentagonal 
  and 
  comparatively 
  lai 
  

  

  The 
  hydrospires 
  are 
  arranged 
  in 
  eight 
  groups, 
  of 
  from 
  8 
  to 
  '.' 
  to 
  

   each 
  set, 
  and 
  there 
  are 
  as 
  many 
  slits 
  along 
  the 
  Bloping 
  rides 
  of 
  the 
  

   radial 
  sinus. 
  The 
  two 
  inner 
  slits 
  which 
  are 
  longer 
  than 
  any 
  of 
  the 
  

   leM, 
  are 
  concealed 
  from 
  view 
  by 
  the 
  overhanging 
  Bides 
  of 
  the 
  lan- 
  

   cet-piece. 
  The 
  succeeding 
  ones 
  are 
  visible 
  externally 
  and 
  dec 
  

   in 
  length 
  with 
  the 
  decreasing 
  width 
  of 
  the 
  .sides 
  of 
  the 
  sinus. 
  

   all, 
  however, 
  decrease 
  in 
  that 
  proportion, 
  this 
  is 
  only 
  the 
  case 
  with 
  

   the 
  four 
  or 
  live 
  outer 
  ones, 
  of 
  which 
  the 
  outermost 
  i- 
  but 
  little 
  

   r 
  than 
  wide; 
  the 
  preceding 
  three, 
  from 
  the 
  fourth 
  inward, 
  are 
  

   nearly 
  of 
  equal 
  length. 
  It 
  should 
  also 
  he 
  remarked 
  that 
  the 
  slits 
  

  

  have 
  an 
  irregular 
  outline 
  even 
  in 
  the 
  best 
  preserv< 
  nd 
  it 
  

  

  appears 
  as 
  if 
  there 
  had 
  been 
  pons 
  in 
  place 
  of 
  the 
  slii- 
  

  

  slit 
  opens 
  into 
  a 
  sac. 
  This, 
  however, 
  is 
  so 
  narrow, 
  that 
  the 
  walk 
  

  

  almost 
  touch 
  each 
  other. 
  e\ 
  the 
  lower 
  end. 
  whi 
  Mains 
  

  

  almost 
  tin 
  width 
  of 
  the 
  alternating 
  folds 
  of 
  the 
  by 
  rhere 
  

  

  ii 
  difference 
  in 
  the 
  depth 
  of 
  ti 
  the 
  two 
  inner 
  

  

  . 
  ttend 
  into 
  the 
  body 
  for 
  a 
  comparatively 
  short 
  d 
  

  

  lepth 
  in 
  the 
  same 
  proportion 
  as 
  they 
  

   grow 
  shorter 
  upon 
  the 
  surface 
  of 
  the 
  body. 
  

  

  hitma 
  graeilt 
  is 
  in 
  its 
  form 
  at 
  al 
  habit 
  

  

  moat 
  identical 
  with 
  / 
  ■ 
  ' 
  ■ 
  Eth. 
  and 
  Carp, 
  bat 
  it 
  

  

  of 
  bydj 
  and 
  not 
  ten. 
  It 
  diffi 
  

  

  