﻿34 
  P. 
  H. 
  CABPENTEK 
  OK" 
  SOME 
  NEW 
  OE 
  

  

  stone 
  outside 
  the 
  upper 
  stem-joints, 
  which 
  divided 
  up 
  into 
  segments 
  

   not 
  corresponding 
  with 
  those 
  enclosed 
  by 
  it. 
  

  

  On 
  the 
  other 
  hand, 
  the 
  appearance 
  of 
  some 
  individuals 
  would 
  

   lead 
  one 
  to 
  suppose 
  that 
  the 
  uniformity 
  and 
  relative 
  thickness 
  of 
  the 
  

   top 
  stem-joint 
  are 
  the 
  signs 
  of 
  its 
  age, 
  and 
  that 
  this 
  condition 
  may 
  

   be 
  replaced 
  by 
  one 
  in 
  which 
  this 
  joint 
  is 
  thinner 
  and 
  unequally 
  

   developed, 
  the 
  change 
  being 
  due 
  to 
  the 
  intercalation 
  of 
  a 
  new 
  joint 
  

   immediately 
  beneath 
  the 
  basals. 
  At 
  any 
  rate 
  that 
  is 
  the 
  manner 
  in 
  

   which 
  I 
  should 
  interpret 
  the 
  peculiarities 
  of 
  the 
  specimens 
  shown 
  in 
  

   figs. 
  11, 
  17, 
  & 
  20 
  b. 
  Judging 
  from 
  the 
  two 
  former 
  only, 
  one 
  would 
  

   almost 
  say 
  that 
  this 
  was 
  a 
  type 
  with 
  a 
  dicyclic 
  base 
  like 
  Encrinus 
  ; 
  

   but 
  the 
  latter 
  shows 
  that 
  the 
  apparent 
  underbasals 
  are 
  really 
  the 
  

   disconnected 
  portions 
  of 
  a 
  new 
  top 
  stem-joint. 
  

  

  2. 
  The 
  Basals. 
  

  

  The 
  basals 
  are 
  pentagonal 
  plates 
  with 
  tolerably 
  open 
  upper 
  angles, 
  

   and 
  not 
  quite 
  twice 
  as 
  wide 
  as 
  they 
  are 
  high. 
  As 
  a 
  general 
  rule 
  

   they 
  form 
  a 
  closed 
  circlet, 
  completely 
  separating 
  the 
  radials 
  from 
  

   the 
  top 
  stem-joint 
  (PI. 
  I. 
  figs. 
  1, 
  4b, 
  6-8, 
  10, 
  14). 
  The 
  under- 
  

   surface 
  of 
  this 
  basal 
  circlet 
  is 
  deeply 
  concave, 
  and 
  marked 
  with 
  very 
  

   distinct 
  radiating 
  strise 
  around 
  its 
  margin 
  (fig. 
  16). 
  There 
  are, 
  

   however, 
  many 
  and 
  various 
  irregularities 
  in 
  the 
  structure 
  of 
  the 
  

   base. 
  Thus 
  in 
  one 
  individual 
  three 
  of 
  the 
  basals 
  on 
  one 
  side 
  of 
  the 
  

   calyx 
  are 
  of 
  the 
  ordinary 
  character 
  ; 
  but 
  on 
  the 
  other 
  side 
  one 
  of 
  

   the 
  radials 
  is 
  greatly 
  developed 
  and 
  is 
  in 
  contact 
  with 
  the 
  top 
  stem- 
  

   joint 
  for 
  nearly 
  the 
  whole 
  of 
  its 
  width, 
  while 
  the 
  radial 
  next 
  it 
  is 
  also 
  

   larger 
  than 
  usual, 
  so 
  that 
  the 
  two 
  basals 
  beneath 
  them 
  meet 
  neither 
  

   one 
  another 
  nor 
  their 
  fellows. 
  

  

  Instead 
  of 
  the 
  basals 
  being 
  in 
  complete 
  contact 
  with 
  one 
  another 
  

   all 
  round, 
  they 
  are 
  sometimes 
  separated 
  more 
  or 
  less 
  completely 
  by 
  

   small 
  irregular 
  intermediate 
  plates 
  (PI. 
  I. 
  figs. 
  3, 
  23), 
  while 
  

   between 
  them 
  and 
  the 
  radials 
  the 
  supposed 
  " 
  ovarial 
  openings 
  " 
  are 
  

   sometimes 
  visible, 
  as 
  already 
  mentioned. 
  These 
  were 
  first 
  noticed 
  in 
  

   Apiocrinus 
  rotundus 
  by 
  Miller*, 
  who 
  speaks 
  of 
  " 
  more 
  or 
  less 
  elevated 
  

   tubercles 
  having 
  a 
  central 
  perforation, 
  which, 
  in 
  one 
  instance, 
  I 
  have 
  

   traced 
  to 
  pass 
  through 
  the 
  joint 
  of 
  the 
  pelvis 
  into 
  the 
  space 
  between 
  

   it 
  and 
  the 
  costal 
  joints, 
  extending 
  perhaps 
  thence 
  into 
  the 
  funnel- 
  

   shaped 
  [visceral] 
  cavity. 
  This 
  has 
  suggested 
  to 
  rile 
  the 
  idea 
  that 
  it 
  

   might 
  have 
  led 
  to 
  an 
  ovary 
  having 
  five 
  ducts, 
  somewhat 
  similar 
  to 
  

   that 
  of 
  the 
  Echinus." 
  According 
  to 
  Jelly 
  f, 
  these 
  openings 
  are 
  fre- 
  

   quently 
  almost 
  imperceptible 
  in 
  Ap. 
  rotundus, 
  " 
  whereas 
  in 
  this 
  

   fossil 
  [M. 
  Prattii] 
  they 
  occupy 
  a 
  very 
  considerable 
  place 
  in 
  its 
  ex- 
  

   ternal 
  configuration. 
  Besides 
  this, 
  they 
  are, 
  almost 
  without 
  excep- 
  

   tion, 
  closed 
  with 
  a 
  small 
  plate 
  or 
  plug, 
  as 
  it 
  were 
  ; 
  and 
  this 
  is 
  

   sometimes, 
  though 
  rarely, 
  punctured 
  in 
  the 
  centre." 
  GoldfussJ 
  

   speaks 
  of 
  finding 
  between 
  the 
  radials 
  of 
  one 
  individual 
  "einen 
  Kanal, 
  

   der 
  zur 
  Leibeshohlung 
  fiihrt 
  ;" 
  while, 
  according 
  to 
  d'Orbigny 
  §, 
  the 
  

  

  * 
  A 
  Natural 
  History 
  of 
  the 
  Crinoidea, 
  p. 
  31. 
  

  

  t 
  Loc. 
  cit. 
  p. 
  9 
  of 
  separate 
  copy. 
  

  

  % 
  Op. 
  cit. 
  p. 
  187. 
  § 
  Op. 
  cit. 
  p. 
  80. 
  

  

  