﻿LITTLE 
  -KNOWX 
  JTJEASSIC 
  CRICOIDS. 
  31 
  

  

  structural 
  peculiarities, 
  and 
  I 
  feel 
  proportionately 
  grateful 
  to 
  Prof. 
  

   Hughes 
  for 
  his 
  kindness 
  in 
  entrusting 
  it 
  to 
  me 
  for 
  description. 
  

  

  1. 
  The 
  Stem. 
  

   a. 
  Variation 
  in 
  its 
  length 
  and 
  in 
  the 
  number 
  of 
  its 
  component 
  joints. 
  

  

  The 
  longest 
  stem 
  which 
  I 
  have 
  met 
  with 
  in 
  any 
  individual 
  is 
  that 
  

   represented 
  in 
  PL 
  I. 
  fig. 
  14. 
  It 
  is 
  rather 
  more 
  than 
  50 
  mm. 
  

   in 
  length, 
  and 
  consists 
  of 
  about 
  70 
  joints 
  of 
  a 
  discoidal 
  shape 
  with 
  

   denticulated 
  edges. 
  They 
  are 
  all 
  of 
  about 
  the 
  same 
  height, 
  a 
  few 
  

   here 
  and 
  there 
  being 
  slightly 
  thinner 
  than 
  the 
  rest. 
  The 
  uppermost 
  

   one 
  is 
  but 
  little 
  thicker 
  than 
  those 
  below 
  it, 
  and 
  is 
  of 
  the 
  same 
  shape 
  

   as 
  in 
  all 
  Apiocrinidse, 
  its 
  ventral 
  surface 
  being 
  divided 
  into 
  hollows 
  

   for 
  the 
  reception 
  of 
  the 
  basals 
  by 
  five 
  prominent 
  radial 
  ridges. 
  

   This 
  is 
  indicated 
  on 
  the 
  outside 
  of 
  the 
  calyx 
  by 
  the 
  upper 
  edge 
  of 
  

   the 
  top 
  stem-joint 
  presenting 
  an 
  alternation 
  of 
  elevations 
  and 
  depres- 
  

   sions. 
  The 
  former, 
  radial 
  in 
  position, 
  are 
  the 
  ends 
  of 
  the 
  ridges, 
  

   while 
  the 
  latter 
  mark 
  the 
  synosteal 
  surfaces 
  for 
  the 
  attachment 
  of 
  

   the 
  basals 
  (PL 
  I. 
  fig. 
  12). 
  The 
  stem 
  tapers 
  gradually 
  to 
  about 
  

   the 
  30th 
  joint 
  from 
  the 
  top, 
  below 
  which 
  it 
  is 
  tolerably 
  uniform. 
  

   Its 
  lower 
  end 
  is 
  unfortunately 
  broken 
  away, 
  but 
  the 
  lowest 
  portion 
  

   of 
  what 
  remains 
  seems 
  to 
  be 
  covered 
  with 
  a 
  kind 
  of 
  incrustation 
  

   that 
  obscures 
  the 
  lines 
  of 
  suture 
  of 
  the 
  last 
  six 
  or 
  eight 
  joints. 
  

  

  A 
  very 
  different 
  stem 
  is 
  represented 
  in 
  PL 
  I. 
  fig. 
  6. 
  It 
  is 
  little 
  

   more 
  than 
  half 
  as 
  long 
  (27 
  mm.) 
  as 
  that 
  just 
  described, 
  but 
  has 
  

   nearly 
  as 
  many 
  (about 
  60) 
  joints. 
  It 
  is 
  broken 
  below, 
  but 
  the 
  

   lowest 
  part 
  remaining 
  shows 
  a 
  slight 
  tendency 
  to 
  a 
  beaded 
  appear- 
  

   ance 
  ; 
  for 
  it 
  consists 
  of 
  about 
  25 
  narrow 
  but 
  thick 
  joints, 
  which 
  

   increase 
  very 
  slightly 
  in 
  width 
  from 
  below 
  upwards, 
  and 
  together 
  

   make 
  up 
  more 
  than 
  half 
  of 
  the 
  whole 
  length 
  of 
  the 
  stem. 
  The 
  

   joints 
  immediately 
  above 
  these 
  begin 
  rather 
  suddenly 
  to 
  decrease 
  in 
  

   thickness, 
  but 
  at 
  the 
  same 
  time 
  increase 
  in 
  width, 
  so 
  that 
  the 
  upper 
  

   part 
  of 
  the 
  stem 
  tapers 
  rather 
  rapidly 
  from 
  above 
  downwards. 
  The 
  

   uppermost 
  joints 
  are 
  very 
  short 
  and 
  closely 
  set, 
  and 
  that 
  just 
  under 
  

   the 
  calyx 
  is 
  of 
  the 
  usual 
  shape, 
  the 
  radial 
  ridges 
  being 
  a 
  trifle 
  larger 
  

   than 
  in 
  the 
  last-mentioned 
  specimen. 
  

  

  Another 
  individual 
  (PL 
  I. 
  fig. 
  8) 
  has 
  a 
  stem 
  25 
  mm. 
  long, 
  

   and 
  generally 
  similar 
  to 
  that 
  shown 
  in 
  fig. 
  6, 
  though 
  somewhat 
  

   different 
  in 
  details. 
  It 
  consists 
  of 
  about 
  50 
  joints, 
  the 
  uppermost 
  

   of 
  which 
  are 
  the 
  thickest, 
  while 
  the 
  rest 
  decrease 
  rather 
  rapidly 
  from 
  

   above 
  downwards 
  ; 
  but 
  in 
  the 
  lower 
  part 
  of 
  the 
  stem 
  the 
  joints 
  

   again 
  increase 
  in 
  thickness 
  as 
  if 
  it 
  were 
  going 
  to 
  become 
  beaded. 
  

   The 
  last 
  ones, 
  however, 
  seem 
  to 
  have 
  fused 
  into 
  an 
  irregular 
  slightly 
  

   swollen 
  mass, 
  on 
  which 
  their 
  sutures 
  are 
  somewhat 
  obscured. 
  The 
  

   same 
  peculiarity 
  is 
  visible 
  in 
  the 
  stem-fragment 
  represented 
  in 
  

   PL 
  I. 
  fig. 
  5, 
  which 
  is 
  not 
  only 
  swollen 
  but 
  seems 
  to 
  have 
  a 
  branch 
  

   (root 
  ?) 
  proceeding 
  from 
  it 
  as 
  in 
  some 
  Apiocrinus-stems. 
  

  

  In 
  another 
  case 
  (PL 
  I. 
  fig. 
  7) 
  the 
  stem, 
  which 
  measures 
  23 
  mm. 
  

   in 
  length, 
  tapers 
  downwards 
  rather 
  rapidly 
  at 
  first, 
  but 
  afterwards 
  

  

  