﻿OP 
  FIVE 
  GENERA. 
  OP 
  MESOZOIC 
  KEPTILES. 
  49 
  

  

  In 
  the 
  original 
  description 
  it 
  is 
  stated 
  that 
  the 
  mandible 
  is 
  29-5 
  

   inches 
  in 
  length, 
  of 
  which 
  9*5 
  inches 
  are 
  occupied 
  by 
  the 
  sym- 
  

   physis; 
  and 
  that 
  the 
  teeth 
  rapidly 
  decrease 
  in 
  size 
  towards 
  the 
  

   proximal 
  end 
  of 
  the 
  jaw, 
  in 
  which 
  region 
  they 
  are 
  very 
  small. 
  

   There 
  remain 
  18 
  true 
  cervical 
  vertebrae 
  *, 
  of 
  which 
  the 
  centra 
  are 
  

   slightly 
  cupped, 
  and 
  the 
  cervical 
  ribs 
  are 
  short 
  and 
  wide. 
  The 
  19th 
  

   to 
  the 
  24th 
  vertebrae 
  are 
  described 
  as 
  ' 
  pectoral/ 
  and 
  comprise 
  those 
  

   which 
  are 
  transitional 
  between 
  the 
  true 
  cervicals 
  and 
  dorsals, 
  and 
  

   are 
  characterized 
  by 
  the 
  neurocentral 
  suture 
  descending 
  in 
  a 
  V 
  onto 
  

   the 
  centrum 
  ; 
  while 
  the 
  25th 
  to 
  the 
  46th 
  are 
  reckoned 
  as 
  dorsal. 
  

   "With 
  the 
  exception 
  of 
  some 
  remarks 
  on 
  the 
  humerus 
  and 
  femur, 
  

   the 
  above 
  constitutes 
  the 
  gist 
  of 
  the 
  original 
  description. 
  

  

  Some 
  months 
  ago 
  Mr. 
  G. 
  C. 
  Crick, 
  E.G.S., 
  of 
  the 
  British 
  (Natural 
  

   History) 
  Museum, 
  brought 
  to 
  my 
  notice 
  a 
  considerable 
  portion 
  of 
  

   the 
  skeleton 
  of 
  a 
  medium-sized 
  Sauropterygian, 
  obtained 
  from 
  the 
  

   Oxford 
  Clay 
  of 
  Green-End, 
  Kempston, 
  about 
  three 
  miles 
  south-west 
  

   of 
  Bedford, 
  which 
  at 
  once 
  struck 
  me 
  as 
  presenting 
  several 
  interesting 
  

   features. 
  This 
  specimen 
  (which 
  has 
  been 
  presented 
  to 
  the 
  Museum 
  

   by 
  Mr. 
  Crick, 
  Sen.) 
  I 
  was 
  enabled, 
  during 
  a 
  visit 
  to 
  Cambridge, 
  as 
  

   already 
  mentioned, 
  to 
  identify 
  with 
  Plesiosaurus 
  pliilarchus. 
  When 
  

   found, 
  I 
  have 
  no 
  doubt 
  that 
  the 
  skeleton 
  of 
  this 
  example 
  was 
  entire, 
  

   but 
  it 
  has 
  been 
  sadly 
  broken 
  up 
  during 
  its 
  extraction 
  by 
  the 
  clay- 
  

   diggers. 
  The 
  portions 
  remaining 
  comprise 
  several 
  upper 
  teeth 
  in 
  

   very 
  beautiful 
  preservation 
  ; 
  the 
  greater 
  portion 
  of 
  the 
  mandible, 
  of 
  

   which 
  the 
  symphysial 
  region 
  is 
  entire, 
  although 
  the 
  crowns 
  of 
  the 
  

   teeth 
  have 
  been 
  broken 
  off; 
  a 
  considerable 
  number 
  of 
  vertebrae, 
  

   mostly 
  from 
  the 
  dorsal, 
  lumbar, 
  and 
  caudal 
  regions; 
  the 
  greater 
  

   portion 
  of 
  the 
  two 
  pelvic 
  and 
  pectoral 
  limbs, 
  and 
  a 
  considerable 
  

   part 
  of 
  the 
  corresponding 
  girdles. 
  I 
  have 
  also 
  had 
  the 
  opportunity 
  

   of 
  examining 
  several 
  more 
  or 
  less 
  nearly 
  entire 
  skeletons 
  of 
  the 
  

   same 
  species 
  from 
  the 
  Oxford 
  Clay 
  near 
  Peterborough, 
  in 
  the 
  col- 
  

   lection 
  of 
  Mr. 
  A. 
  N. 
  Leeds 
  of 
  Eyebury, 
  near 
  that 
  town, 
  which 
  have 
  

   afforded 
  important 
  aid 
  in 
  determining 
  the 
  true 
  affinities 
  of 
  this 
  

   species. 
  In 
  the 
  main 
  my 
  description 
  will 
  be 
  based 
  on 
  the 
  Bedford 
  

   skeleton, 
  but 
  I 
  shall 
  supplement 
  its 
  deficiencies 
  by 
  reference 
  to 
  the 
  

   other 
  specimens. 
  

  

  It 
  will 
  save 
  trouble 
  to 
  state 
  at 
  starting 
  that 
  I 
  regard 
  this 
  form 
  as 
  

   indicating 
  a 
  new 
  genus, 
  for 
  which 
  I 
  shall 
  propose 
  the 
  name 
  PeTo- 
  

   neustes. 
  

  

  Commencing 
  the 
  description 
  with 
  the 
  mandible, 
  it 
  appears 
  that 
  

   on 
  the 
  right 
  side 
  there 
  are 
  38 
  teeth, 
  and 
  since 
  the 
  symphysis 
  slightly 
  

   exceeds 
  9 
  inches 
  in 
  length, 
  it 
  will 
  be 
  evident 
  that 
  this 
  specimen 
  

   accords 
  exactly 
  in 
  these 
  respects 
  with 
  the 
  type. 
  And 
  it 
  may 
  be 
  

   added 
  that 
  another 
  mandible 
  from 
  the 
  Oxford 
  Clay 
  of 
  Peterborough 
  

   in 
  the 
  British 
  Museum 
  (No. 
  47411) 
  also 
  agrees 
  with 
  these 
  

   dimensions. 
  The 
  first 
  seven 
  mandibular 
  teeth 
  are 
  very 
  large 
  ; 
  the 
  

   eighth 
  is 
  somewhat 
  smaller 
  ; 
  while 
  the 
  9th 
  and 
  following 
  teeth 
  are 
  

   considerably 
  smaller. 
  Thirteen 
  teeth 
  are 
  included 
  in 
  the 
  symphysis. 
  

  

  * 
  Professor 
  Seeley 
  counts 
  the 
  conjoint 
  atlas 
  and 
  axis 
  as 
  a 
  single 
  vertebra. 
  

  

  Q. 
  J. 
  G. 
  S. 
  No. 
  177. 
  e 
  

  

  