﻿H. 
  G. 
  SEELEY 
  ON 
  NETJSTICOSATJRTJS 
  PTJSILLTJS. 
  . 
  351 
  

  

  The 
  superior 
  aspect 
  of 
  the 
  skull 
  is 
  remarkable 
  for 
  the 
  large 
  size 
  of 
  

   the 
  temporal 
  fossse, 
  orbits, 
  and 
  nostrils, 
  the 
  latter 
  having 
  a 
  very 
  forward 
  

   position. 
  The 
  palate, 
  on 
  the 
  other 
  hand, 
  is 
  remarkable 
  for 
  its 
  extensive 
  

   ossification 
  (pi. 
  17) 
  ; 
  and, 
  as 
  Professor 
  Owen 
  has 
  observed, 
  the 
  ptery- 
  

   goids 
  form 
  a 
  broad, 
  expanded, 
  unbroken, 
  flat, 
  imperforate 
  expanse 
  of 
  

   bone, 
  united 
  by 
  a 
  median 
  suture, 
  and 
  underlapping 
  the 
  sphenoid. 
  The 
  

   only 
  large 
  perforations 
  on 
  the 
  palate 
  are 
  those 
  beneath 
  the 
  anterior 
  

   nares 
  and 
  those 
  external 
  to 
  the 
  pterygoids. 
  If 
  we 
  now 
  turn 
  to 
  

   the 
  skull 
  of 
  the 
  little 
  animal 
  figured 
  by 
  Dr. 
  Praas, 
  the 
  exposed 
  

   surface, 
  which 
  he 
  identifies 
  as 
  the 
  palate, 
  shows 
  exactly 
  that 
  

   arrangement 
  of 
  vacuities 
  which 
  von 
  Meyer 
  figures 
  (pi. 
  18) 
  as 
  

   distinctive 
  of 
  the 
  superior 
  surface 
  of 
  the 
  head. 
  There 
  is, 
  however, 
  

   no 
  reason 
  to 
  question 
  the 
  accuracy 
  of 
  Dr. 
  Praas's 
  topographical 
  iden- 
  

   tification, 
  since 
  the 
  exposed 
  surface 
  is 
  concave, 
  as 
  only 
  the 
  palate 
  

   could 
  be, 
  shows 
  alveoli, 
  and 
  has 
  no 
  trace 
  of 
  a 
  parietal 
  foramen, 
  

   though 
  the 
  bones 
  are 
  too 
  perfectly 
  ossified 
  and 
  blended 
  to 
  permit 
  of 
  

   their 
  individual 
  definition 
  in 
  detail. 
  But 
  such 
  a 
  palate 
  as 
  the 
  

   specimen 
  exhibits 
  makes 
  reference 
  of 
  the 
  species 
  to 
  JSimosaurus 
  

   impossible. 
  Equally 
  impossible 
  is 
  it 
  to 
  refer 
  the 
  type 
  to 
  any 
  other 
  

   genus 
  hitherto 
  instituted. 
  The 
  difference, 
  indeed, 
  is 
  of 
  a 
  subordinal 
  

   rather 
  than 
  a 
  generic 
  quality 
  ; 
  for 
  since 
  all 
  the 
  allied 
  Triassic 
  genera 
  

   hitherto 
  known 
  have 
  the 
  palate 
  closed, 
  in 
  harmony 
  with 
  the 
  Plesio- 
  

   saurian 
  plan 
  (and 
  it 
  may 
  be 
  in 
  relation 
  to 
  aquatic 
  conditions 
  of 
  life), 
  

   here 
  we 
  may 
  have 
  an 
  indication 
  of 
  the 
  kind 
  of 
  skull 
  from 
  which 
  the 
  

   Plesiosaurian 
  type 
  was 
  originally 
  derived. 
  It 
  has 
  therefore 
  

   appeared 
  desirable 
  to 
  offer 
  to 
  the 
  Society 
  some 
  further 
  details 
  of 
  the 
  

   anatomical 
  structure 
  of 
  this 
  animal, 
  which 
  I 
  was 
  enabled 
  to 
  study 
  

   by 
  the 
  courtesy 
  of 
  Mr. 
  Hoser, 
  before 
  the 
  skeletons 
  became 
  finally 
  

   deposited 
  in 
  the 
  national 
  collection 
  at 
  South 
  Kensington. 
  

  

  The 
  larger 
  specimen 
  (PL 
  XIII. 
  fig. 
  1) 
  lies 
  on 
  the 
  back 
  in 
  a 
  slight 
  

   sigmoid 
  curve, 
  and 
  exposes 
  the 
  abdominal 
  aspect 
  of 
  the 
  skeleton, 
  all 
  

   the 
  bones 
  of 
  which 
  are 
  in 
  situ 
  except 
  some 
  elements 
  of 
  the 
  pectoral 
  

   girdle, 
  the 
  abdominal 
  ribs, 
  and 
  parts 
  of 
  the 
  limbs, 
  which 
  are 
  lost. 
  The 
  

   extreme 
  length 
  of 
  this 
  skeleton 
  as 
  it 
  lies 
  hardly 
  exceeds 
  270 
  mm., 
  

   though 
  Mr. 
  Hoser 
  measuring 
  the 
  separate 
  regions 
  makes 
  it 
  285 
  mm. 
  

  

  The 
  second 
  and 
  somewhat 
  smaller 
  individual 
  (PI. 
  XIII. 
  fig. 
  3) 
  ex- 
  

   poses 
  the 
  dorsal 
  aspect 
  of 
  the 
  bones, 
  but 
  has 
  lost 
  the 
  head 
  and 
  anterior 
  

   part 
  of 
  the 
  neck, 
  the 
  extremity 
  of 
  the 
  tail, 
  some 
  of 
  the 
  smaller 
  limb- 
  

   bones, 
  and 
  the 
  right 
  hind 
  limb. 
  But 
  though 
  the 
  conformation 
  of 
  the 
  

   bones 
  is 
  slightly 
  different 
  in 
  this 
  animal, 
  the 
  differences 
  are 
  no 
  more 
  

   than 
  may 
  perhaps 
  be 
  attributed 
  to 
  sex 
  or 
  age. 
  

  

  The 
  Head. 
  

  

  The 
  head 
  (PL 
  XIII. 
  fig. 
  2) 
  is 
  nearly 
  3 
  cm. 
  long, 
  and 
  is 
  14 
  mm. 
  wide 
  

   in 
  the 
  posterior 
  or 
  quadrate 
  region, 
  where 
  it 
  is 
  widest 
  : 
  the 
  sides 
  are 
  

   at 
  first 
  nearly 
  parallel, 
  and 
  then 
  taper 
  forward 
  in 
  a 
  lanceolate 
  shape. 
  

   It 
  lies 
  flat, 
  and 
  has 
  been 
  carefully 
  excavated 
  so 
  as 
  to 
  display 
  the 
  

   several 
  regions 
  of 
  the 
  palate. 
  In 
  front, 
  resting 
  close 
  upon 
  the 
  

   maxillary 
  bones, 
  there 
  appears 
  to 
  be 
  a 
  small 
  fragment 
  of 
  the 
  lower 
  

  

  

  