﻿32 
  P. 
  H. 
  CARPENTER 
  ON 
  SOME 
  NEW 
  OR 
  

  

  more 
  slowly. 
  Except 
  for 
  some 
  irregularities 
  to 
  be 
  noticed 
  hereafter, 
  

   all 
  the 
  joints 
  to 
  just 
  above 
  the 
  lower 
  end 
  are 
  wide 
  and 
  tolerably 
  

   thick 
  disks. 
  The 
  last 
  two 
  are 
  so 
  closely 
  united 
  that 
  the 
  suture 
  

   between 
  them 
  is 
  scarcely 
  visible 
  ; 
  and 
  the 
  under 
  surface 
  of 
  the 
  

   lowest 
  joint 
  is 
  rounded 
  off 
  without 
  any 
  trace 
  of 
  striations, 
  while 
  its 
  

   central 
  opening, 
  which 
  is 
  at 
  the 
  bottom 
  of 
  a 
  shallow 
  pit, 
  is 
  closed 
  up. 
  

   Whether 
  it 
  was 
  open 
  or 
  not 
  throughout 
  life 
  must 
  of 
  course 
  remain 
  

   uncertain, 
  just 
  as 
  in 
  the 
  case 
  of 
  Comatulce 
  with 
  more 
  or 
  less 
  marked 
  

   pits 
  on 
  the 
  lower 
  surface 
  of 
  the 
  centrodorsal. 
  The 
  same 
  remark 
  

   applies 
  to 
  two 
  other 
  stems 
  (PI. 
  I. 
  figs. 
  11, 
  12). 
  One 
  is 
  17 
  mm. 
  

   long, 
  and 
  consists 
  of 
  about 
  16 
  rather 
  thick 
  joints, 
  the 
  lowest 
  of 
  

   which 
  is 
  rounded 
  off, 
  while 
  the 
  other 
  is 
  but 
  10 
  mm. 
  long 
  and 
  is 
  

   composed 
  of 
  15 
  joints. 
  In 
  another 
  specimen, 
  on 
  the 
  other 
  hand, 
  the 
  

   stem, 
  though 
  containing 
  20 
  joints, 
  is 
  only 
  8 
  mm. 
  long. 
  Other 
  instances 
  

   are 
  (1) 
  stem 
  of 
  9 
  joints, 
  8| 
  mm. 
  long 
  ; 
  (2) 
  stem 
  of 
  7 
  joints, 
  6| 
  mm. 
  

   long 
  (PI. 
  I. 
  fig. 
  1), 
  both 
  of 
  them 
  rounded 
  off 
  below. 
  

  

  The 
  next 
  specimen 
  to 
  be 
  considered 
  (PI. 
  I. 
  fig. 
  13) 
  is 
  one 
  with 
  

   a 
  short 
  conical 
  stem, 
  4 
  mm. 
  in 
  length 
  and 
  composed 
  of 
  5 
  joints, 
  the 
  

   lowest 
  of 
  which 
  is 
  quite 
  small 
  and 
  rounded 
  off 
  without 
  any 
  trace 
  of 
  

   a 
  central 
  perforation. 
  This 
  leads 
  us 
  to 
  a 
  couple 
  of 
  individuals 
  

   (PI. 
  I. 
  figs. 
  2, 
  23) 
  that 
  might 
  readily 
  be 
  mistaken 
  for 
  cirrhus- 
  

   less 
  Comatulce, 
  all 
  that 
  represents 
  the 
  stem 
  being 
  a 
  couple 
  of 
  

   flattened 
  joints 
  situated 
  beneath 
  the 
  basals 
  and 
  closing 
  in 
  the 
  calyx 
  

   below. 
  Fig. 
  18 
  shows 
  that 
  even 
  one 
  of 
  these 
  may 
  be 
  absent, 
  the 
  

   basals 
  resting 
  on 
  a 
  slightly 
  convex 
  pentagonal 
  plate 
  without 
  any 
  

   central 
  perforation. 
  It 
  is 
  very 
  interesting 
  to 
  compare 
  this 
  figure 
  

   with 
  fig. 
  22, 
  which 
  represents 
  the 
  concave 
  striated 
  facet 
  on 
  the 
  

   under 
  surface 
  of 
  the 
  top 
  stem-joint 
  of 
  a 
  stalked 
  individual. 
  The 
  

   two 
  or 
  three 
  joints 
  immediately 
  below 
  the 
  uppermost 
  one 
  present 
  

   differences 
  of 
  a 
  similar 
  kind, 
  according 
  as 
  they 
  belong 
  to 
  individuals 
  

   with 
  quite 
  short 
  or 
  with 
  longer 
  stems. 
  In 
  the 
  former 
  case 
  (PI. 
  I. 
  

   figs. 
  3, 
  17, 
  20 
  b) 
  their 
  under 
  surface 
  is 
  concave, 
  perforate, 
  and 
  

   striated 
  ; 
  but 
  if 
  they 
  be 
  the 
  lowest 
  joints 
  of 
  the 
  short 
  stems 
  (PI. 
  I. 
  

   figs. 
  2, 
  4, 
  13, 
  23) 
  they 
  are 
  imperforate, 
  rounded 
  off 
  below, 
  and 
  

   exhibit 
  no 
  indications 
  of 
  striation. 
  

  

  Here, 
  then, 
  within 
  the 
  limits 
  of 
  what 
  is 
  obviously 
  but 
  a 
  single 
  

   species, 
  we 
  meet 
  with 
  a 
  most 
  remarkable 
  series 
  of 
  transitions 
  from 
  

   the 
  pedunculate 
  to 
  the 
  free 
  mode 
  of 
  existence. 
  But 
  the 
  difference 
  

   between 
  the 
  two 
  is 
  of 
  less 
  physiological 
  importance 
  than 
  it 
  was 
  

   formerly 
  considered 
  to 
  be. 
  Por 
  some 
  Pentacrinus- 
  species, 
  although 
  

   stalked 
  and 
  attached 
  when 
  young, 
  seem 
  when 
  mature 
  to 
  be 
  

   practically 
  free 
  in 
  their 
  mode 
  of 
  life, 
  while 
  others 
  are 
  fixed 
  by 
  a 
  

   slightly 
  spreading 
  base*. 
  Such 
  a 
  "free 
  " 
  Pentacrinus 
  is 
  P. 
  Wyville- 
  

   Thomsonif, 
  and, 
  according 
  to 
  de 
  LoriolJ, 
  the 
  fossil 
  P. 
  briar 
  eus 
  and 
  

   its 
  allies 
  led 
  a 
  similar 
  independent 
  existence; 
  but 
  in 
  both 
  these 
  

   cases 
  the 
  portion 
  of 
  stem 
  which 
  remains 
  in 
  connexion 
  with 
  the 
  

  

  * 
  Bull. 
  Mus. 
  Comp. 
  Zool.vol. 
  v. 
  no. 
  14, 
  p. 
  296. 
  

   t 
  The 
  Depths 
  of 
  the 
  Sea, 
  p. 
  444. 
  

  

  % 
  Notice 
  sur 
  le 
  Pentacrinus 
  de 
  Sennecey-le-Grand, 
  Chalon-sur-Saone, 
  1878, 
  

   p. 
  12. 
  

  

  