﻿H. 
  Gr. 
  SEELEY 
  ON 
  NEtTSTICOSATTKTTS 
  PUSILLUS. 
  353 
  

  

  tal 
  condyle 
  is 
  small 
  and 
  globular. 
  On 
  each 
  side 
  of 
  it 
  there 
  is 
  a 
  

   strong 
  lateral 
  bony 
  mass 
  as 
  big 
  as 
  the 
  condyle 
  itself, 
  but 
  separated 
  

   by 
  an 
  inferior 
  groove, 
  as 
  is 
  often 
  seen 
  in 
  the 
  basioccipital 
  bone 
  of 
  

   Plesiosaurs. 
  

  

  The 
  way 
  in 
  which 
  this 
  skull 
  diverges 
  from 
  Plesiosaurus 
  or 
  

   Notliosaurus, 
  suggests 
  a 
  distinct 
  approximation 
  to 
  Lizards. 
  And 
  

   there 
  are 
  many 
  lizards 
  in 
  which 
  the 
  palate 
  might, 
  by 
  a 
  median 
  

   blending 
  of 
  the 
  pterygoid 
  bones, 
  present 
  a 
  similar 
  aspect. 
  

  

  An 
  approximation 
  to 
  such 
  a 
  palate 
  is 
  offered 
  by 
  the 
  common 
  

   Lacerta 
  agilis, 
  though 
  the 
  superior 
  surfaces 
  of 
  the 
  two 
  skulls 
  are 
  not 
  

   likely 
  to 
  show 
  any 
  thing 
  in 
  common. 
  The 
  distinctive 
  feature 
  of 
  the 
  

   lizard 
  palate 
  consists 
  in 
  the 
  presence 
  of 
  the 
  vacuities 
  which 
  result 
  

   from 
  the 
  pterygoid 
  bones 
  abutting 
  against 
  anterior 
  augles 
  of 
  the 
  

   sphenoid, 
  so 
  that 
  they 
  do 
  not 
  completely 
  meet 
  in 
  the 
  middle 
  line. 
  

   Even 
  in 
  Ampliisbcena 
  the 
  structure 
  of 
  the 
  palate, 
  with 
  the 
  ptery- 
  

   goids 
  external 
  to 
  the 
  basisphenoid, 
  is 
  hardly 
  an 
  exception 
  to 
  the 
  

   Lizard 
  plan, 
  though 
  the 
  pterygo-sphenoid 
  vacuities 
  are 
  so 
  far 
  reduced 
  

   as 
  to 
  make 
  the 
  palate 
  essentially 
  Chelonian. 
  It 
  is 
  therefore 
  pro- 
  

   bable 
  that 
  the 
  Lizard-like 
  conformation 
  in 
  this 
  fossil, 
  is 
  not 
  indicative 
  

   of 
  Lacertilian 
  affinities, 
  at 
  least 
  of 
  affinity 
  towards 
  any 
  surviving 
  

   type 
  of 
  the 
  group. 
  It 
  is 
  at 
  first 
  sight 
  as 
  difficult 
  to 
  see 
  any 
  resem- 
  

   blance 
  in. 
  it 
  to 
  the 
  Plesiosaur 
  as 
  to 
  distinguish 
  it 
  from 
  the 
  Lizard 
  ; 
  

   for 
  the 
  backward 
  position 
  of 
  the 
  external 
  nares 
  towards 
  the 
  middle 
  

   of 
  the 
  head 
  in 
  Plesiosaurs 
  necessarily 
  gives 
  rise 
  to 
  a 
  difference 
  of 
  

   proportion 
  in 
  the 
  palatal 
  regions, 
  and 
  causes 
  the 
  posterior 
  nares 
  

   to 
  be 
  carried 
  backward 
  so 
  as 
  to 
  approximate 
  to 
  the 
  Crocodilian 
  plan 
  

   (see 
  Owen, 
  Monog. 
  iii. 
  Eept. 
  Kim. 
  Clay, 
  t. 
  i. 
  fig. 
  1, 
  also 
  Rept. 
  of 
  Lias, 
  

   t. 
  xvi.). 
  Put 
  if 
  the 
  premaxillary 
  bones 
  had 
  not 
  extended 
  their 
  pos- 
  

   terior 
  margins 
  backward 
  so 
  as 
  to 
  remove 
  the 
  external 
  nares 
  from 
  the 
  

   extremity 
  of 
  the 
  snout, 
  then 
  probably 
  the 
  palate 
  of 
  Plesiosaurus 
  would 
  

   have 
  compared 
  better 
  with 
  our 
  fossil; 
  for 
  the 
  lateral 
  vacuities 
  in 
  the 
  

   palate 
  might 
  then 
  have 
  held 
  a 
  more 
  forward 
  position. 
  But 
  in 
  any 
  

   case 
  Plesiosaurus 
  has 
  no 
  representative 
  of 
  the 
  vacuities 
  which 
  occupy 
  

   the 
  middle 
  of 
  the 
  palate, 
  and 
  are 
  margined 
  posteriorly 
  by 
  the 
  trans- 
  

   verse 
  bones, 
  any 
  more 
  than 
  has 
  Notliosaurus 
  or 
  Simosaurus, 
  in 
  both 
  

   of 
  which 
  the 
  palatal 
  nares 
  are 
  as 
  far 
  forward. 
  

  

  Vertebral 
  Column. 
  

  

  The 
  neck 
  (PL 
  XIII. 
  fig. 
  1) 
  is 
  twice 
  or 
  twice 
  and 
  a 
  half 
  as 
  long 
  as 
  the 
  

   head. 
  It 
  includes 
  about 
  20 
  vertebree 
  ; 
  but 
  the 
  state 
  of 
  preservation 
  is 
  

   such 
  as 
  to 
  present 
  considerable 
  difficulty 
  in 
  determining 
  which 
  should 
  

   be 
  taken 
  as 
  the 
  last 
  cervical 
  ; 
  and 
  it 
  may 
  be 
  that 
  some 
  would 
  prefer 
  to 
  

   count 
  only 
  17 
  vertebra?. 
  The 
  length 
  of 
  the 
  cervical 
  vertebras 
  appears 
  

   to 
  vary 
  but 
  little, 
  though 
  the 
  centrums 
  increase 
  in 
  size 
  as 
  they 
  recede 
  

   from 
  the 
  head 
  and 
  approach 
  the 
  back. 
  The 
  cervical 
  region, 
  however^ 
  

   is 
  not 
  so 
  well 
  preserved 
  as 
  to 
  show 
  the 
  exact 
  form 
  of 
  the 
  bones. 
  There 
  

   is 
  no 
  clear 
  evidence 
  of 
  the 
  form 
  and 
  characters 
  of 
  the 
  articular 
  face 
  of 
  

   the 
  centrum 
  ; 
  in 
  the 
  lower 
  part 
  of 
  the 
  neck 
  the 
  base 
  of 
  the 
  centrum 
  

   appears 
  to 
  be 
  grooved. 
  I 
  am 
  unable 
  to 
  recognize 
  any 
  cervical 
  ribs 
  

  

  