﻿14 
  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  BRACHYDECTES, 
  Cope. 
  

   Proceed. 
  Ac. 
  Nat. 
  Sci., 
  Phila., 
  18C8, 
  214. 
  

  

  This 
  genus 
  is 
  indicated 
  by 
  two 
  rami 
  of 
  a 
  mandible 
  and 
  a 
  portion 
  of 
  a 
  premaxillary 
  

   only. 
  These, 
  when 
  compared 
  with 
  those 
  of 
  (Estocephalus, 
  and 
  Dendrerpeton, 
  from 
  the 
  

   same 
  locality, 
  and 
  with 
  others 
  described 
  by 
  authors, 
  are 
  so 
  much 
  stouter, 
  i. 
  e., 
  shorter 
  

   and 
  more 
  elevated, 
  that 
  they 
  evidently 
  belonged 
  to 
  a 
  genus 
  not 
  hitherto 
  known. 
  The 
  

   genus 
  further 
  differs 
  from 
  Oestocephalus, 
  in 
  having 
  the 
  teeth 
  of 
  equal 
  size 
  to 
  the 
  poste- 
  

   rior 
  parts 
  of 
  the 
  series, 
  that 
  is, 
  to 
  the 
  base 
  of 
  the 
  elevated 
  coronoid 
  process. 
  The 
  teeth 
  

   are 
  elongate 
  cylindric 
  cones, 
  with 
  their 
  acute 
  tips 
  turned 
  a 
  little 
  posteriorly. 
  The 
  frac- 
  

   tured 
  ones 
  display 
  a 
  large 
  pulp 
  cavity. 
  The 
  three 
  premaxillaries 
  preserved 
  are 
  similar, 
  

   but 
  without 
  curvature 
  of 
  the 
  tips. 
  They 
  do 
  not 
  exhibit 
  strise 
  or 
  any 
  other 
  sculpture. 
  

  

  So 
  far 
  as 
  the 
  remains 
  known 
  go, 
  the 
  genus 
  is 
  nearer 
  Hylerpeton 
  than 
  any 
  other. 
  

   According 
  to 
  Dawson 
  that 
  genus 
  is 
  provided 
  with 
  a 
  large 
  canine-like 
  tooth, 
  at 
  the 
  ante- 
  

   rior 
  extremity 
  of 
  the 
  maxillary, 
  on 
  the 
  inner 
  row, 
  which 
  is 
  inserted 
  into 
  a 
  distinct 
  socket. 
  

   No 
  such 
  tooth 
  appears 
  among 
  those 
  of 
  this 
  genus. 
  The 
  latter 
  does 
  not 
  give 
  any 
  indica- 
  

   tion 
  of 
  the 
  very 
  elevated 
  coronoid 
  process 
  of 
  Brachydectes, 
  though 
  the 
  external 
  portion 
  

   of 
  the 
  dentary 
  bone 
  in 
  that 
  region 
  being 
  lost, 
  little 
  can 
  be 
  said 
  about 
  it. 
  Prof. 
  Owen's 
  

   plate 
  indicates 
  a 
  ramus 
  whose 
  depth 
  at 
  the 
  last 
  tooth 
  enters 
  8| 
  times 
  the 
  total 
  length. 
  

   In 
  our 
  species 
  this 
  depth 
  enters 
  about 
  5 
  times. 
  

  

  BRACHYDECTES 
  NEWBERRYI, 
  Cope. 
  

  

  This 
  species 
  is 
  represented 
  by 
  one 
  nearly 
  perfect 
  ramus 
  mandibuli, 
  one 
  dentary 
  bone, 
  and 
  one 
  premaxillary, 
  prob- 
  

   ably 
  not 
  complete. 
  

  

  The 
  dentary 
  bone 
  appears 
  to 
  have 
  been 
  attached 
  by 
  suture 
  to 
  the 
  articular 
  and 
  angular, 
  as 
  its 
  free 
  margin 
  has 
  

   very 
  much 
  the 
  outline 
  of 
  that 
  suture 
  in 
  Amphiuma 
  and 
  lizards. 
  The 
  coronoid 
  process 
  would 
  also 
  seem 
  to 
  be 
  a 
  part 
  

   of 
  the 
  same 
  bone 
  as 
  in 
  Amphiuma 
  and 
  Menopoma, 
  and 
  not 
  composed 
  of 
  a 
  coronoid 
  bone 
  as 
  in 
  lizards. 
  It 
  rises 
  im- 
  

   mediately 
  behind 
  the 
  last 
  tooth, 
  and 
  displays 
  no 
  suture. 
  

  

  The 
  lower 
  portion 
  of 
  the 
  dentary 
  is 
  prolonged 
  into 
  an 
  acute 
  angle. 
  This 
  is 
  separated 
  by 
  a 
  deep 
  and 
  wide 
  con- 
  

   cavity 
  from 
  the 
  superior 
  posterior 
  prolongation, 
  which 
  is 
  obtuse 
  and 
  rises 
  at 
  once 
  into 
  the 
  coronoid 
  process. 
  Teeth 
  

   on 
  this 
  dentary 
  seven 
  ; 
  the 
  same 
  number 
  is 
  on 
  the 
  preserved 
  ramus 
  ; 
  this 
  number 
  is 
  suspected 
  to 
  be 
  complete 
  or 
  

   naerly 
  so. 
  The 
  teeth 
  terminate 
  at 
  the 
  obvious 
  termination 
  of 
  each 
  ramus, 
  which 
  is, 
  it 
  is 
  true, 
  slightly 
  obscured. 
  

   These 
  teeth 
  are 
  the 
  longest 
  of 
  the 
  Microsauria 
  in 
  relation 
  to 
  the 
  depth 
  of 
  the 
  ramus, 
  equalling 
  the 
  largest 
  in 
  (Esto- 
  

   cephalus. 
  They 
  are 
  doubtless 
  exposed, 
  as 
  are 
  some 
  of 
  those 
  of 
  the 
  last 
  named 
  genus, 
  by 
  the 
  splitting 
  away 
  of 
  the 
  

   outer 
  parapet 
  of 
  the 
  dentary 
  bone. 
  As 
  no 
  traces 
  of 
  alveoli 
  have 
  been 
  thus 
  rendered 
  visible, 
  I 
  suspect 
  the 
  dentition 
  

   to 
  have 
  been 
  acrodont, 
  as 
  in 
  some 
  existing 
  Batrachia. 
  

  

  No 
  external 
  surface 
  of 
  the 
  mandible 
  remains, 
  but 
  there 
  are 
  no 
  impressions 
  of 
  sculpture 
  on 
  the 
  matrix. 
  A 
  little 
  

   external 
  face 
  of 
  the 
  premaxillary 
  displays 
  none. 
  

  

  