﻿202 
  H. 
  G. 
  SEELEY 
  ON 
  HTK^NOSAUEUS 
  LEEDSII, 
  

  

  rises 
  more 
  than 
  2 
  inches 
  above 
  the 
  zygapophysial 
  ridge, 
  while 
  the 
  

   vertebra 
  measures 
  4f 
  inches 
  in 
  extreme 
  height. 
  In 
  the 
  middle 
  of 
  

   the 
  neck 
  the 
  articular 
  surface 
  of 
  the 
  centrum 
  becomes 
  much 
  more 
  

   circular, 
  and 
  appears 
  to 
  be, 
  relatively 
  to 
  its 
  size, 
  rather 
  less 
  deeply 
  

   cupped. 
  In 
  the 
  twenty-fourth 
  vertebra 
  the 
  centrum 
  is 
  2^ 
  inches 
  

   from 
  side 
  to 
  side 
  in 
  front, 
  and 
  1-| 
  inch 
  from 
  above 
  downward 
  ; 
  at 
  

   tbe 
  side 
  it 
  measures 
  more 
  than 
  2| 
  inches 
  from 
  back 
  to 
  front. 
  

   The 
  circumference 
  of 
  the 
  articular 
  surface 
  has 
  now 
  become 
  rough- 
  

   ened 
  for 
  the 
  attachment 
  of 
  small 
  connecting 
  vertebral 
  ligaments. 
  

   The 
  upper 
  part 
  of 
  the 
  body 
  of 
  the 
  centrum 
  remains 
  still 
  greatly 
  

   compressed 
  from 
  side 
  to 
  side. 
  The 
  extreme 
  height 
  to 
  the 
  top 
  of 
  the 
  

   neural 
  arch 
  is 
  5f 
  inches; 
  the 
  zygapophysial 
  ridge 
  is 
  nearly 
  horizontal; 
  

   and 
  the 
  sharp 
  anterior 
  process 
  of 
  the 
  neural 
  spine 
  extends 
  forward 
  

   between 
  the 
  anterior 
  zygapophyses 
  of 
  that 
  vertebra, 
  and 
  divides 
  the 
  

   posterior 
  zygapophyses 
  of 
  the 
  preceding 
  vertebra 
  from 
  each 
  other 
  ; 
  

   the 
  neural 
  canal 
  is 
  remarkably 
  small 
  and 
  triangular, 
  higher 
  than 
  

   wide, 
  and 
  higher 
  behind 
  than 
  in 
  front. 
  

  

  In 
  the 
  thirty-third 
  vertebra 
  (fig. 
  2) 
  the 
  centrum 
  is 
  2| 
  inches 
  long, 
  

   in 
  front 
  2| 
  inches 
  deep, 
  and 
  about 
  T 
  *g- 
  to 
  g 
  of 
  an 
  inch 
  wider. 
  The 
  

   articular 
  surfaces 
  are 
  relatively 
  flatter, 
  while 
  the 
  margin 
  external 
  to 
  

   the 
  epiphyses 
  is 
  now 
  becoming 
  wider. 
  The 
  posterior 
  articular 
  sur- 
  

   face 
  is 
  about 
  2| 
  inches 
  wide 
  and 
  2| 
  inches 
  deep. 
  The 
  zyga- 
  

   pophyses 
  are, 
  in 
  front, 
  on 
  their 
  inner 
  articular 
  surfaces 
  concave 
  from 
  

   above 
  downward, 
  so 
  that 
  they 
  almost 
  meet 
  in 
  a 
  median 
  line, 
  forming 
  

   the 
  lower 
  half 
  of 
  a 
  cylinder. 
  The 
  extreme 
  height 
  to 
  the 
  top 
  of 
  the 
  

   neural 
  arch 
  is 
  7 
  inches 
  ; 
  the 
  extreme 
  width 
  over 
  the 
  zygapophyses 
  

   is 
  3J 
  inches 
  ; 
  the 
  antero-posterior 
  extent 
  of 
  the 
  top 
  of 
  the 
  neural 
  

   spine 
  is 
  If 
  inch 
  ; 
  the 
  anterior 
  border 
  of 
  the 
  neural 
  spine 
  is 
  slightly 
  

   concave 
  from 
  above 
  downward. 
  Between 
  the 
  posterior 
  zygapophyses, 
  

   convex 
  from 
  above 
  downward, 
  there 
  is 
  a 
  median 
  slit 
  into 
  which 
  the 
  

   lower 
  anterior 
  margin 
  of 
  the 
  neural 
  spine 
  of 
  the 
  succeeding 
  vertebra 
  

   is 
  wedged, 
  thus 
  constituting 
  a 
  new 
  kind 
  of 
  vertebral 
  joint, 
  compa- 
  

   rable 
  in 
  complexity 
  to 
  that 
  of 
  Iguanoid 
  lizards 
  and 
  serpents, 
  though 
  

   of 
  somewhat 
  different 
  mechanism 
  and 
  function. 
  

  

  In 
  the 
  thirty-ninth 
  vertebra 
  (fig. 
  3) 
  the 
  neural 
  canal 
  becomes 
  con- 
  

   siderably 
  larger 
  ; 
  the 
  vertebral 
  articular 
  surfaces 
  are 
  becoming 
  flatter 
  ; 
  

   the 
  cervical 
  ribs 
  are 
  wider 
  in 
  their 
  attachment, 
  and 
  incline 
  more 
  

   markedly 
  to 
  the 
  posterior 
  border 
  of 
  the 
  centrum 
  : 
  this 
  vertebra 
  has 
  an 
  

   exostosis 
  on 
  the 
  right 
  posterior 
  articular 
  margin 
  ; 
  its 
  height 
  to 
  the 
  

   top 
  of 
  the 
  neural 
  spine 
  is 
  rather 
  more 
  than 
  7| 
  inches. 
  The 
  neural 
  

   spine 
  is 
  1-| 
  inch 
  from 
  back 
  to 
  front 
  in 
  the 
  middle. 
  The 
  neural 
  spine 
  

   reaches 
  its 
  extreme 
  height 
  in 
  the 
  fortieth 
  vertebra, 
  where 
  it 
  extends 
  

   to 
  7J 
  inches. 
  The 
  posterior 
  zygapophyses 
  are 
  margined 
  above 
  by 
  

   a 
  slightly 
  elevated 
  ridge. 
  

  

  In 
  the 
  last 
  cervical, 
  the 
  articulation 
  for 
  the 
  rib, 
  which 
  in 
  the 
  three 
  

   preceding 
  vertebras 
  has 
  been 
  rising 
  on 
  the 
  side 
  of 
  the 
  centrum 
  and 
  

   becoming 
  circular 
  and 
  elevated, 
  is 
  now 
  higher 
  than 
  wide 
  and 
  in- 
  

   clined 
  a 
  little 
  backward. 
  The 
  centrum 
  increases 
  in 
  flatness, 
  and 
  the 
  

   neural 
  spine 
  is 
  inclined 
  slightly 
  backward 
  ; 
  the 
  articular 
  edges 
  are 
  

   more 
  than 
  usually 
  compressed 
  and 
  expanded 
  ; 
  and 
  the 
  nutritive 
  fora- 
  

  

  