﻿356 
  H. 
  G. 
  SEELEY 
  ON 
  NETTSTICOSATTKUS 
  PTJSILLTIS. 
  

  

  tail, 
  as 
  preserved, 
  is 
  5 
  cm. 
  long, 
  but 
  shows 
  no 
  indication 
  of 
  being 
  

   near 
  the 
  end 
  where 
  it 
  terminates. 
  In 
  this 
  length 
  the 
  vertebrae 
  are 
  

   compressed 
  from 
  side 
  to 
  side, 
  and 
  have 
  the 
  transverse 
  processes 
  less 
  

   robust 
  than 
  in 
  the 
  larger 
  specimen. 
  The 
  processes 
  become 
  shorter, 
  

   and 
  in 
  the 
  last 
  3 
  or 
  4 
  vertebrae 
  are 
  only 
  indicated 
  by 
  tubercles. 
  

   Hence 
  in 
  the 
  larger 
  or 
  type 
  specimen 
  the 
  vertebral 
  formula 
  appears 
  

   to 
  be 
  17 
  cervical. 
  29 
  dorsal, 
  1 
  sacral, 
  and 
  15 
  caudal. 
  

  

  The 
  Ribs. 
  

  

  The 
  large 
  specimen 
  (PI. 
  XIII. 
  fig. 
  1) 
  has 
  the 
  ribs 
  spread 
  out 
  on 
  each 
  

   side 
  of 
  the 
  vertebral 
  column 
  symmetrically 
  and 
  in 
  natural 
  positiou, 
  

   except 
  for 
  a 
  slight 
  displacement 
  on 
  the 
  right 
  side 
  of 
  the 
  body 
  in 
  the 
  

   pectoral 
  region. 
  Seven 
  vertebrae 
  anterior 
  to 
  the 
  humerus 
  have 
  ribs 
  ; 
  

   the 
  first 
  of 
  these 
  may 
  belong 
  to 
  the 
  cervical 
  region. 
  The 
  next 
  four 
  

   may 
  also 
  belong 
  to 
  the 
  neck, 
  but 
  the 
  two 
  immediately 
  in 
  front 
  of 
  the 
  

   humerus 
  are 
  probably 
  to 
  be 
  counted 
  as 
  dorsal. 
  Reckoning 
  in 
  this 
  

   way, 
  there 
  are 
  22 
  or 
  23 
  pairs 
  of 
  ribs 
  with 
  corresponding 
  vertebrae 
  

   anterior 
  to 
  the 
  pubis, 
  all 
  of 
  which 
  must 
  be 
  reckoned 
  as 
  dorsal. 
  The 
  

   length 
  of 
  this 
  region 
  is 
  about 
  98 
  mm. 
  The 
  width 
  across 
  the 
  ribs 
  

   and 
  vertebral 
  column 
  as 
  they 
  lie 
  is 
  34 
  mm. 
  in 
  the 
  middle, 
  narrow- 
  

   ing 
  a 
  little 
  towards 
  the 
  anterior 
  and 
  posterior 
  ends, 
  owing 
  to 
  the 
  

   ribs 
  becoming 
  somewhat 
  shorter. 
  The 
  ribs 
  are 
  curved 
  ; 
  measured 
  

   from 
  end 
  to 
  end 
  without 
  regarding 
  the 
  curve, 
  they 
  are 
  about 
  

   2 
  cm. 
  long. 
  Cylindrical 
  in 
  the 
  abdominal 
  two 
  thirds, 
  they 
  are 
  

   expanded, 
  thickened, 
  and 
  enlarged 
  towards 
  the 
  articulation 
  with 
  

   the 
  vertebra. 
  The 
  thickening 
  appears 
  to 
  have 
  been 
  greatest 
  from 
  

   above 
  downward 
  ; 
  and, 
  as 
  already 
  remarked, 
  there 
  is 
  a 
  sort 
  of 
  notch 
  

   at 
  the 
  articular 
  end, 
  different 
  from 
  what 
  is 
  observed 
  in 
  any 
  Plesio- 
  

   saur, 
  and 
  highly 
  suggestive 
  of 
  a 
  double 
  articulation, 
  though 
  not 
  in- 
  

   consistent 
  with 
  the 
  Lizard 
  type. 
  No 
  specimen 
  shows 
  the 
  articular 
  

   facet, 
  but 
  the 
  corresponding 
  facet 
  on 
  the 
  neural 
  arch 
  always 
  exhibits 
  

   a 
  pit. 
  

  

  In 
  the 
  smaller 
  specimen 
  (PL 
  XIII. 
  fig. 
  3) 
  the 
  ribs 
  are 
  more 
  nearly 
  

   in 
  natural 
  position, 
  but 
  their 
  distal 
  ends 
  are 
  crushed 
  together 
  so 
  as 
  to 
  

   be 
  absolutely 
  in 
  contact. 
  The 
  principal 
  bones 
  of 
  the 
  pelvis 
  and 
  of 
  the 
  

   scapular 
  arch 
  are 
  hidden 
  ; 
  but 
  I 
  do 
  not 
  think 
  more 
  than 
  22 
  pairs 
  of 
  

   ribs 
  could 
  properly 
  be 
  reckoned 
  as 
  dorsal. 
  The 
  proximal 
  ends 
  of 
  

   the 
  ribs 
  appear 
  to 
  be 
  relatively 
  larger 
  and 
  more 
  cylindrical 
  than 
  in 
  

   the 
  other 
  specimen, 
  and 
  the 
  interspaces 
  between 
  the 
  ribs 
  appear 
  to 
  

   be 
  less, 
  though 
  in 
  no 
  case 
  is 
  the 
  interspace 
  equal 
  to 
  the 
  width 
  of 
  the 
  

   rib 
  itself, 
  as 
  they 
  lie. 
  The 
  transverse 
  width 
  across 
  the 
  ribs 
  in 
  the 
  

   small 
  specimen 
  is 
  little 
  more 
  than 
  2 
  cm. 
  

  

  In 
  the 
  remarkable 
  elongation 
  of 
  the 
  neck 
  and 
  proportions 
  of 
  the 
  

   vertebral 
  column, 
  the 
  characters 
  are 
  entirely 
  Plesiosaurian 
  ; 
  but, 
  for 
  

   a 
  member 
  of 
  this 
  group, 
  the 
  intercentral 
  surfaces 
  are 
  remarkably 
  

   flat 
  ; 
  and 
  unless 
  the 
  apparent 
  blending 
  of 
  the 
  early 
  dorsal 
  centrums 
  

   iu 
  the 
  region 
  of 
  the 
  coracoids 
  is 
  an 
  accidental 
  character, 
  it 
  makes 
  a 
  

   marked 
  difference 
  from 
  known 
  Plesiosaurians. 
  The 
  appearance 
  of 
  

   pegging 
  together 
  in 
  the 
  neural 
  arch 
  has, 
  at 
  first 
  sight, 
  a 
  suggestion 
  

   of 
  the 
  mode 
  of 
  union 
  of 
  the 
  neural 
  arches 
  of 
  certain 
  Lizards 
  and 
  

  

  