﻿26 
  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  These 
  I 
  suspected 
  to 
  indicate 
  the 
  positions 
  of 
  inflections 
  of 
  enamel, 
  as 
  it 
  is 
  difficult 
  to 
  imagine 
  such 
  regularly 
  

   radiating 
  fractures. 
  I 
  cannot 
  however, 
  be 
  entirely 
  sure 
  that 
  this 
  is 
  the 
  case. 
  Under 
  a 
  low 
  power 
  neither 
  the 
  

   radii 
  nor 
  interspaces 
  exhibit 
  any 
  structure 
  ; 
  the 
  small 
  pulp 
  cavity 
  is 
  filled 
  with 
  the 
  sandstone 
  matrix 
  in 
  which 
  the 
  

   tooth 
  is 
  enclosed. 
  It 
  may 
  be 
  supposed 
  that 
  the 
  relatively 
  denser 
  structure 
  of 
  the 
  enamel 
  has 
  been 
  preserved 
  in 
  the 
  

   slow 
  alteration 
  which 
  the 
  composition 
  of 
  the 
  tooth 
  has 
  undergone. 
  They 
  thus 
  project 
  on 
  weathered 
  or 
  ground 
  surfaces. 
  

  

  The 
  species 
  to 
  which 
  these 
  teeth 
  pertain 
  was 
  originally 
  described 
  by 
  the 
  writer 
  as 
  a 
  Mastodonsaurus. 
  The 
  

   latter 
  genus 
  however 
  exhibits 
  external 
  grooves 
  where 
  the 
  inflections 
  of 
  enamel 
  enter 
  and 
  separate 
  the 
  dentine. 
  These 
  

   inflections, 
  as 
  is 
  well 
  known 
  from 
  the 
  figures 
  and 
  descriptions 
  of 
  Professor 
  Owen, 
  are 
  more 
  or 
  less 
  convoluted, 
  some 
  

   of 
  them 
  very 
  highly 
  so. 
  The 
  laminse 
  of 
  the 
  teeth 
  of 
  the 
  Eupelor 
  cannot 
  be 
  looked 
  upon 
  as 
  inflections 
  of 
  enamel, 
  but 
  

   rather 
  as 
  branches. 
  They 
  are 
  exceedingly 
  thin, 
  and 
  our 
  sections 
  do 
  not 
  demonstrate 
  them 
  to 
  be 
  double. 
  If 
  they 
  are 
  

   double, 
  they 
  are 
  very 
  much 
  more 
  attenuated 
  than 
  the 
  external 
  enamel 
  stratum. 
  They 
  may 
  be 
  distinguished 
  in 
  a 
  

   section 
  of 
  the 
  wall 
  of 
  the 
  pulp 
  cavity 
  at 
  the 
  base 
  of 
  the 
  root 
  as 
  well 
  as 
  elsewhere. 
  

  

  The 
  fluted 
  tooth 
  referred 
  to 
  in 
  my 
  original 
  description, 
  in 
  which 
  this 
  structure 
  is 
  observable, 
  belongs 
  apparently 
  

   to 
  a 
  Thecodont, 
  perhaps 
  to 
  Belodon 
  : 
  other 
  teeth 
  of 
  this 
  genus 
  which 
  I 
  have 
  seen 
  present 
  the 
  same 
  peculiarity. 
  As 
  the 
  

   tooth 
  from 
  which 
  the 
  description 
  of 
  Eupelor 
  was 
  derived, 
  is 
  from 
  the 
  same 
  stratum 
  as 
  the 
  Belodon 
  and 
  Clepsysaurus, 
  

   and 
  some 
  distance 
  above 
  the 
  horizon 
  of 
  the 
  cranial 
  bones 
  described, 
  after 
  an 
  examination 
  of 
  the 
  series 
  in 
  possession 
  

   of 
  Wheatley, 
  I 
  am 
  disposed 
  to 
  refer 
  all 
  these 
  teeth 
  to 
  the 
  Thecodonts, 
  and 
  restrict 
  the 
  name 
  Eupelor 
  durus 
  m. 
  to 
  the 
  

   cranial 
  bones 
  only. 
  

  

  Class 
  II.-EEPTILIA. 
  

  

  The 
  following 
  preliminary 
  table 
  exhibits 
  the 
  more 
  essential 
  characters 
  of 
  the 
  orders 
  

   of 
  Reptilia, 
  as 
  understood 
  by 
  the 
  writer 
  :* 
  

  

  I. 
  Supratemporal 
  and 
  postorbital 
  bones 
  present 
  ; 
  extremital 
  portions 
  of 
  limbs 
  not 
  

   differentiated 
  ; 
  quadrate 
  bone 
  united 
  by 
  sutures. 
  

  

  ICHTHTOPTERYGIA. 
  

  

  II. 
  No 
  supratemporal 
  or 
  postorbital 
  bones 
  ; 
  extremital 
  portions 
  of 
  limbs 
  differentiated. 
  

   A 
  The 
  quadrate 
  bone 
  united 
  by 
  suture 
  to 
  the 
  prootic, 
  the 
  opisthotic 
  and 
  the 
  quadra- 
  

  

  tojugal 
  bones. 
  

  

  « 
  The 
  scapular 
  arch 
  continuous, 
  including 
  the 
  sternum, 
  which 
  is 
  anterior 
  and 
  simple. 
  

  

  ARCHOSAURIA. 
  

  

  aa 
  Scapular 
  arch 
  not 
  continuous, 
  sternum 
  inferior, 
  extending 
  posteriorly, 
  composed 
  of 
  

   at 
  least 
  eight 
  elements 
  : 
  dorsal 
  vertebrae 
  sacrum-like. 
  

  

  TESTUDINATA. 
  

  

  A 
  A 
  The 
  quadrate 
  bone 
  not 
  united 
  with 
  the 
  prootic, 
  and 
  articulating 
  freely 
  with 
  the 
  

   opisthotic 
  ; 
  no 
  quadratojugal. 
  (Streptostylica.) 
  

  

  Sacrum 
  from 
  three 
  to 
  five 
  vertebrae; 
  anterior 
  extremities 
  excessively 
  elongated 
  for 
  

   flight 
  ; 
  acetabulum 
  complete 
  ; 
  pubes 
  longitudinal, 
  distinct 
  ; 
  exoccipital 
  not 
  distinct. 
  

  

  PTEROSAURIA. 
  

  

  * 
  Many 
  of 
  these 
  groups 
  correspond 
  with 
  those 
  proposed 
  by 
  Prof. 
  Owen. 
  

  

  