﻿178 
  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  to, 
  and 
  analogous 
  with, 
  the 
  suspensorium 
  of 
  the 
  Ophidia 
  ; 
  hence 
  I 
  conclude 
  that 
  the 
  lat- 
  

   ter 
  bone 
  is 
  the 
  opisthotic, 
  and 
  not 
  squamosal, 
  as 
  given 
  by 
  Huxley- 
  (Elements 
  Compar. 
  

   Anatomy) 
  ; 
  and 
  the 
  more, 
  as 
  it 
  co-exists 
  with 
  a 
  true 
  squamosal 
  in 
  these 
  extinct 
  reptiles. 
  

   Internally 
  it 
  forms 
  a 
  very 
  small 
  or 
  no 
  part 
  of 
  the 
  wall 
  of 
  the 
  cranium, 
  but 
  is 
  a 
  solid 
  plug 
  

   between 
  the 
  embracing 
  laminae 
  of 
  the 
  prootic 
  and 
  exoccipital. 
  The 
  two 
  latter 
  bones 
  are 
  

   therefore 
  unusually 
  and 
  peculiarly 
  prolonged 
  outwards, 
  and 
  unite 
  by 
  thin 
  edges 
  on 
  both 
  

   the 
  upper 
  and 
  inferior 
  faces 
  of 
  the 
  suspensorium. 
  The 
  fenestra 
  ovale 
  is 
  at 
  the 
  base 
  of 
  the 
  

   infero-posterior 
  face 
  of 
  the 
  latter, 
  and 
  enters 
  an 
  exceedingly 
  small 
  vestibule. 
  The 
  fenes- 
  

   tra 
  rotunda 
  is 
  immediately 
  below 
  it, 
  and 
  is 
  funnel-shaped, 
  with 
  a 
  small 
  orifice. 
  In 
  the 
  

   small 
  development 
  of 
  the 
  auditory 
  apparatus 
  it 
  is 
  again 
  like 
  the 
  serpents. 
  

  

  The 
  mandibular 
  arch 
  is 
  very 
  much 
  like 
  that 
  of 
  serpents. 
  The 
  lack 
  of 
  symphysis 
  gave 
  

   each 
  ramus 
  the 
  independent 
  motion 
  which 
  they 
  possess 
  in 
  the 
  Ophidia, 
  The 
  articulation 
  

   of 
  the 
  splenial 
  and 
  subarticular 
  is 
  a 
  character 
  not 
  seen 
  in 
  any 
  lacertian, 
  but 
  is 
  highly 
  char- 
  

   acteristic 
  of 
  the 
  Boaeform 
  Serpents 
  of 
  the 
  genera 
  Loxocemus 
  and 
  Eryx, 
  though 
  it 
  does 
  not 
  

   occur 
  in 
  Boa 
  proper, 
  nor 
  in 
  many 
  other 
  serpents. 
  This 
  has 
  allowed 
  of 
  some 
  motion 
  

   as 
  the 
  bones 
  of 
  the 
  ramus 
  above 
  it 
  are 
  merely 
  united 
  by 
  a 
  squamosal 
  suture, 
  and 
  the 
  den- 
  

   tary 
  terminates 
  abruptly 
  between 
  a 
  sheath 
  of 
  the 
  coronoid, 
  etc. 
  This 
  termination, 
  with 
  

   the 
  articular 
  faces 
  of 
  the 
  inferior 
  elements, 
  are 
  characteristic 
  of 
  fragments 
  not 
  uncommon 
  

   in 
  the 
  Cretaceous 
  beds, 
  and 
  which 
  have 
  never 
  in 
  this 
  country 
  been 
  referred 
  to 
  their 
  

   place. 
  The 
  coronoid 
  bone 
  also 
  is 
  developed 
  only 
  as 
  in 
  the 
  few 
  serpents 
  that 
  possess 
  it, 
  as 
  

   Eryx, 
  Xenopeltis, 
  and 
  Boa; 
  Goldfuss 
  notices 
  its 
  great 
  anterior 
  prolongation 
  and 
  curva- 
  

   ture, 
  and 
  overlapping 
  of 
  the 
  extremity 
  of 
  the 
  dentary. 
  Finally 
  the 
  obtuseness 
  and 
  abbre- 
  

   viation 
  of 
  the 
  angle 
  of 
  the 
  jaw 
  is 
  Ophidian 
  — 
  rarely 
  lacertian. 
  The 
  distinctness 
  of 
  the 
  an- 
  

   gular 
  bone 
  is 
  on 
  the 
  other 
  hand 
  a 
  lacertian 
  feature. 
  

  

  The 
  postero-lateral 
  margin 
  of 
  the 
  parietal 
  is 
  decurved 
  and 
  is 
  connected 
  to 
  the 
  sphe- 
  

   noid 
  by 
  a 
  lateral 
  plate 
  of 
  bone, 
  which 
  is 
  united 
  suturally 
  to 
  the 
  latter. 
  I 
  have 
  been 
  una- 
  

   ble 
  to 
  find 
  in 
  Clidastes 
  any 
  suture 
  indicating 
  that 
  this 
  piece 
  is 
  an 
  alisphenoid, 
  rather 
  than 
  

   the 
  parietal 
  ; 
  it 
  appears 
  to 
  belong 
  to 
  the 
  latter 
  bone. 
  If 
  so, 
  it 
  is 
  a 
  strong 
  Ophidian 
  char- 
  

   acter 
  ; 
  if 
  it 
  be 
  alisphenoid, 
  it 
  is 
  Chelonian 
  and 
  Crocodilian 
  ; 
  no 
  Lacertilian 
  presents 
  a 
  like 
  

   structure. 
  

  

  In 
  the 
  genus 
  Clidastes 
  the 
  pterygoid 
  bones 
  are 
  distinct 
  except 
  at 
  their 
  anterior 
  extrem- 
  

   ity, 
  and 
  bear 
  a 
  long 
  series 
  (17 
  e. 
  g.,) 
  of 
  teeth, 
  resembling 
  thus 
  the 
  serpents. 
  

  

  The 
  vertebral 
  column 
  resembles 
  in 
  many 
  features 
  that 
  of 
  the 
  serpents. 
  It 
  is 
  longer, 
  

   and 
  contains 
  more 
  numerous 
  vertebrae 
  than 
  Lacertilian 
  or 
  Saurian 
  types, 
  and 
  has 
  

   therefore 
  a 
  much 
  more 
  slender 
  form 
  than 
  they. 
  The 
  ribs 
  are 
  cylindric, 
  as 
  in 
  lizards 
  and 
  

   serpents, 
  and 
  are 
  present 
  throughout 
  the 
  long 
  dorsal 
  and 
  lumbar 
  series 
  of 
  vertebrae, 
  form- 
  

   ing 
  a 
  much 
  longer 
  series, 
  and 
  embracing 
  a 
  more 
  Ophidian 
  visceral 
  cavity 
  than 
  is 
  seen 
  in 
  

  

  