﻿142 
  J. 
  W. 
  HTTLKE 
  ON 
  SOME 
  IGUANODON-EEMAINS. 
  

  

  and 
  it 
  also 
  obliquely 
  cuts 
  off 
  the 
  lower 
  part 
  of 
  the 
  terminal 
  articular 
  

   surfaces, 
  which 
  gives 
  to 
  these 
  a 
  very 
  square 
  contour. 
  The 
  articular 
  

   surfaces 
  are 
  both 
  concave, 
  the 
  anterior 
  very 
  slightly 
  so, 
  the 
  posterior 
  

   very 
  decidedly. 
  In 
  the 
  latter 
  surface 
  (in 
  the 
  third 
  centrum 
  of 
  the 
  

   series) 
  the 
  bottom 
  of 
  the 
  concavity 
  lies 
  1*6 
  centim. 
  (J 
  in.) 
  in 
  front 
  

   of 
  a 
  plane 
  laid 
  through 
  the 
  circumference. 
  The 
  horizontal 
  diameter 
  

   of 
  this 
  surface, 
  below 
  the 
  level 
  of 
  the 
  transverse 
  process, 
  is 
  13-7 
  cen- 
  

   tim. 
  (5§- 
  in.), 
  which 
  is 
  reduced 
  to 
  12-7 
  centim. 
  (5 
  in.) 
  at 
  its 
  lowest 
  

   limit, 
  where 
  it 
  is 
  cut 
  off 
  by 
  the 
  chevron-facet. 
  The 
  vertical 
  dia- 
  

   meter 
  of 
  the 
  surface 
  is 
  equal 
  to 
  the 
  side 
  of 
  the 
  square, 
  11/7 
  centim, 
  

   (4fin.). 
  

  

  The 
  neural 
  canal 
  was 
  very 
  small: 
  the 
  transverse 
  measurement 
  

   of 
  its 
  floor 
  is 
  under 
  3 
  centim. 
  (1-J- 
  in.) 
  ; 
  and 
  its 
  height 
  is 
  less. 
  The 
  

   neurapophyses 
  are 
  stout 
  ; 
  their 
  attachment 
  to 
  the 
  centrum 
  is 
  nearly 
  

   coequal 
  with 
  the 
  antero-posterior 
  extent 
  of 
  this 
  latter. 
  The 
  neural 
  

   spines, 
  strong 
  flattened 
  blades, 
  having 
  an 
  antero-posterior 
  expansion 
  

   of 
  7*5 
  centim. 
  (3 
  in.), 
  rake 
  backwards, 
  and 
  form 
  with 
  a 
  plane 
  

   through 
  the 
  neural 
  surface 
  of 
  the 
  centrum 
  an 
  angle 
  of 
  about 
  125°. 
  

   Their 
  length 
  was 
  plainly 
  considerable 
  : 
  that 
  of 
  the 
  best-preserved 
  

   one 
  is 
  19 
  centim. 
  (7| 
  in.) 
  ; 
  and 
  it 
  has 
  evidently 
  been 
  broken 
  at 
  some 
  

   distance 
  from 
  its 
  true 
  end. 
  

  

  A 
  long 
  and 
  stout 
  transverse 
  process 
  stands 
  off 
  from 
  the 
  junction 
  

   of 
  the 
  lateral 
  and 
  upper 
  surfaces 
  of 
  the 
  centrum. 
  It 
  is 
  a 
  hori- 
  

   zontally 
  flattened 
  blade 
  with 
  a 
  slight 
  backward 
  curve. 
  Its 
  average 
  

   width 
  is 
  6 
  centim. 
  (2|- 
  in.). 
  The 
  vertical 
  diameter 
  of 
  the 
  process 
  

   near 
  its 
  root 
  is 
  3 
  centim. 
  (Lj- 
  in.), 
  which 
  is 
  reduced 
  to 
  1-4 
  centim. 
  

   at 
  the 
  distance 
  of 
  15 
  centim. 
  (5-^- 
  in.). 
  Its 
  length 
  when 
  entire 
  

   was 
  probably 
  not 
  much 
  more. 
  

  

  Relatively 
  to 
  the 
  great 
  bulk 
  of 
  the 
  vertebra 
  the 
  zygapophyses 
  

   are 
  small 
  ; 
  the 
  front 
  pair 
  project 
  forwards 
  and 
  slightly 
  outwards 
  

   directly 
  above 
  the 
  crown 
  of 
  the 
  arch 
  ; 
  their 
  articular 
  surfaces 
  look 
  

   inwards 
  and 
  slightly 
  forwards. 
  The 
  postzygapophyses 
  have 
  an 
  oval 
  

   articular 
  surface 
  4 
  centim. 
  by 
  3 
  centim. 
  (If 
  by 
  1-J 
  in.). 
  

  

  Dislocated, 
  but 
  cemented 
  to 
  the 
  centrum 
  by 
  rock, 
  are 
  parts 
  of 
  three 
  

   chevron 
  bones. 
  In 
  two 
  of 
  these, 
  the 
  basal 
  end 
  which 
  articulated 
  

   with 
  the 
  vertebral 
  centrum 
  is 
  well 
  preserved. 
  It 
  consists 
  of 
  two 
  

   crescen 
  tic 
  parts, 
  of 
  which 
  the 
  anterior 
  is 
  the 
  larger, 
  meeting 
  angularly. 
  

   A 
  depression 
  in 
  the 
  anterior 
  division 
  received 
  a 
  corresponding 
  

   swelling 
  in 
  the 
  posterior 
  facet 
  of 
  the 
  vertebral 
  centrum 
  when 
  the 
  

   chevrons 
  were 
  articulated. 
  The 
  forked 
  portion 
  of 
  the 
  chevrons 
  is 
  

   12*5 
  centim. 
  (4^ 
  in.) 
  long. 
  The 
  undivided 
  blade, 
  when 
  entire, 
  

   certainly 
  much 
  exceeded 
  this 
  ; 
  and 
  I 
  think 
  it 
  not 
  improbable 
  that 
  the 
  

   length 
  of 
  an 
  entire 
  chevron 
  attained 
  45 
  centim. 
  (17f 
  in.). 
  Other 
  

   detached 
  chevron 
  bones 
  have 
  nearly 
  the 
  above 
  dimensions. 
  

  

  In 
  their 
  transverse 
  processes 
  and 
  chevrons 
  we 
  have 
  the 
  clue 
  to 
  the 
  

   place 
  of 
  these 
  vertebrae 
  in 
  the 
  tail. 
  

  

  Other 
  remains 
  referable 
  to 
  2". 
  Mantelli 
  obtained 
  by 
  me 
  in 
  the 
  same 
  

   locality 
  afford 
  evidence 
  that 
  the 
  foremost 
  chevron 
  bone 
  is 
  intercalated 
  

   between 
  the 
  second 
  and 
  third 
  caudal 
  vertebrae, 
  and 
  that 
  the 
  second 
  

   centrum 
  has 
  but 
  one 
  chevron-facet, 
  from 
  which 
  it 
  is 
  apparent 
  that 
  the 
  

   three 
  vertebrae 
  just 
  described 
  occurred 
  later 
  in 
  the 
  series. 
  In 
  /. 
  

   Mantelli, 
  as 
  in 
  Hypsilopliodon 
  Foxii, 
  the 
  transverse 
  processes 
  of 
  the 
  

  

  