﻿216 
  

  

  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  the 
  same 
  time 
  the 
  splenial 
  articulation 
  is 
  strongly 
  flexed, 
  and 
  the 
  inferior 
  outline 
  of 
  the 
  

   ramus 
  angulate 
  at 
  that 
  point. 
  

  

  We 
  have 
  in 
  this 
  feature 
  one 
  of 
  the 
  most 
  extraordinary 
  peculiarities 
  of 
  this 
  remarkable 
  

   genus. 
  The 
  mandibular 
  arch 
  in 
  its 
  usual 
  relations 
  enclosed 
  a 
  diamond-shaped 
  area, 
  open 
  

   behind, 
  the 
  portion 
  anterior 
  to 
  the 
  lateral 
  angles 
  the 
  longer, 
  and 
  only 
  closed 
  by 
  ligament 
  

   in 
  front. 
  The 
  structure 
  is 
  an 
  element 
  of 
  weakness, 
  though 
  indeed 
  without 
  such 
  an 
  articu- 
  

   lation, 
  such 
  a 
  light 
  and 
  slender 
  jaw 
  would 
  be 
  particularly 
  liable 
  to 
  fracture. 
  There 
  was, 
  

   no 
  doubt 
  a 
  strong 
  ligamentous 
  union 
  of 
  the 
  parts, 
  as 
  the 
  grooved 
  adjacent 
  margins 
  testify, 
  

   but 
  for 
  any 
  supernumerary 
  muscles 
  to 
  flex 
  the 
  dentary 
  bones, 
  I 
  can 
  find 
  no 
  provision. 
  

  

  Fig. 
  51. 
  

  

  1 
  Angular. 
  

  

  2 
  Articular. 
  

  

  3 
  Subarticular. 
  

  

  4 
  Coronoid. 
  

  

  Fig. 
  52. 
  

  

  „ 
  I 
  Splenial. 
  

   7 
  Dentary. 
  

  

  The 
  accompanying 
  cut 
  shows 
  the 
  appearance 
  of 
  the 
  normal 
  flexure 
  of 
  the 
  ramus. 
  The 
  line 
  a 
  I> 
  is 
  that 
  which 
  

   exposes 
  the 
  section 
  given 
  on 
  a 
  preceding- 
  page 
  ; 
  c 
  is 
  the 
  splenial 
  articulation; 
  d 
  the 
  coronoid 
  process, 
  and 
  e 
  the 
  quad- 
  

   rate 
  cotylus. 
  

  

  I 
  am 
  disposed 
  to 
  regard 
  the 
  structure 
  in 
  question 
  as 
  an 
  aid 
  to 
  deglutition, 
  and 
  that 
  

   when 
  large 
  bodies 
  were 
  to 
  be 
  swallowed 
  whole, 
  they 
  passed 
  between 
  the 
  rami, 
  and 
  were 
  

   accommodated 
  by 
  a 
  large 
  extensible 
  pharyngeal 
  cavity, 
  and 
  oesophagus. 
  No 
  doubt 
  some 
  

   remarkable 
  habit 
  was 
  possessed 
  by 
  the 
  animals 
  thus 
  characterized, 
  Avith 
  "which 
  we 
  will 
  

   with 
  difficulty 
  become 
  acquainted. 
  

  

  There 
  is 
  one 
  point 
  in 
  which 
  the 
  composition 
  of 
  the 
  articulation 
  differs 
  from 
  that 
  of 
  

   Eryx 
  and 
  other 
  serpents 
  with 
  which 
  I 
  have 
  compared 
  it. 
  Instead 
  of 
  being 
  formed 
  in 
  its 
  

   posterior 
  member 
  by 
  the 
  subarticular 
  bone, 
  that 
  bone 
  with 
  a 
  portion 
  of 
  the 
  angular 
  is 
  

   sheathed 
  by 
  one 
  more 
  external, 
  which 
  by 
  its 
  position 
  and 
  form, 
  appears 
  to 
  be 
  the 
  

   posterior 
  extremity 
  of 
  the 
  splenial. 
  If, 
  as 
  is 
  probable 
  from 
  a 
  careful 
  study 
  of 
  the 
  parts, 
  

   this 
  is 
  the. 
  case, 
  the 
  splenial 
  must 
  be 
  regarded 
  as 
  a 
  divided 
  bone. 
  

  

  The 
  cut 
  of 
  the 
  inner 
  face 
  of 
  the 
  right 
  ramus, 
  expresses 
  the 
  relations 
  of 
  these 
  pieces. 
  

   Size, 
  4 
  nature. 
  

  

  