﻿12 
  

  

  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  DENDRERPETON, 
  Owen. 
  

   Journal 
  Geological 
  Society, 
  London, 
  1853, 
  p. 
  81. 
  

  

  Iii 
  the 
  form 
  of 
  the 
  cranium 
  this 
  genus 
  differs 
  from 
  Brachydectes 
  and 
  oestocephalus 
  

   much 
  as 
  Menopoma 
  does 
  from 
  Amphiuma. 
  Two 
  species 
  appear 
  to 
  have 
  left 
  their 
  remains 
  

   in 
  the 
  coal 
  measures 
  at 
  Linton, 
  Ohio. 
  

  

  There 
  is 
  an 
  internal 
  as 
  well 
  as 
  an 
  external 
  suries 
  of 
  maxillary 
  teeth 
  in 
  this 
  genus, 
  and 
  

   a 
  vomerine 
  patch, 
  according 
  to 
  Dawson. 
  The 
  skin 
  was 
  ornamented 
  with 
  osseous 
  scales 
  

   of 
  an 
  oval 
  form, 
  some 
  of 
  which 
  >vere 
  longer 
  than 
  others, 
  and 
  formed 
  crest-like 
  series 
  along 
  

   the 
  side. 
  In 
  a 
  specimen 
  of 
  the 
  mandible 
  of 
  the 
  D. 
  acadianum, 
  kindly 
  sent 
  me 
  by 
  Prof. 
  

   Dawson, 
  the 
  inflection 
  of 
  enamel 
  at 
  the 
  base 
  of 
  the 
  tooth 
  is 
  readily 
  observed, 
  but 
  it 
  appears 
  

   to 
  be 
  as 
  smooth 
  as 
  in 
  any 
  other 
  type 
  of 
  the 
  Microsauria 
  above 
  the 
  alveolar 
  margin. 
  

  

  Fig. 
  l. 
  

  

  DENDRERPETON 
  OBTTJSUM, 
  Cope 
  

  

  This 
  species 
  is 
  known 
  by 
  a 
  partially 
  preserved 
  cranium. 
  The 
  

   superior 
  surface 
  is 
  exposed, 
  the 
  outlines 
  of 
  the 
  jaws 
  and 
  orbits 
  are 
  

   well 
  preserved, 
  with 
  the 
  occipital 
  condyles. 
  The 
  os 
  quadratum 
  is 
  

   directed 
  obliquely 
  backwards, 
  and 
  the 
  angle 
  of 
  the 
  mandible 
  extends 
  

   to 
  a 
  line 
  a 
  little 
  behind 
  that 
  of 
  the 
  occipital 
  condyles. 
  The 
  

   zygomatic 
  arch 
  exists 
  in 
  a 
  position 
  similar 
  to 
  that 
  in 
  which 
  it 
  may 
  

   be 
  seen 
  in 
  a 
  few 
  genera 
  of 
  Anura, 
  as 
  Discoglossus 
  and 
  Pelobates. 
  

   It 
  extends 
  downwards 
  and 
  forwards 
  from 
  the 
  supra-squamosal 
  to 
  the 
  

   maxillary 
  region, 
  but 
  whether 
  it 
  is 
  homologically 
  squamosal 
  or 
  

   malar 
  the 
  specimen 
  cannot 
  show. 
  The 
  postorbital 
  is 
  present 
  as 
  

   well, 
  and 
  with 
  the 
  last, 
  and 
  the 
  supratemporal, 
  forms 
  the 
  bony 
  roof 
  

   of 
  the 
  temporal 
  fossa. 
  A 
  piece 
  which 
  may 
  be 
  the 
  pre 
  and 
  post 
  

   frontals 
  combined, 
  borders 
  the 
  inner 
  superior 
  margin 
  of 
  the 
  orbit, 
  it 
  

   widens 
  posteriorly, 
  where 
  it 
  has 
  contact 
  with 
  the 
  parietal, 
  etc., 
  and 
  

   narrows 
  in 
  front. 
  Supraoccipitals 
  form 
  together 
  a 
  broad 
  triangle 
  

   on 
  the 
  upper 
  plane 
  of 
  the 
  cranium, 
  of 
  less 
  extent 
  than 
  the 
  adjoining 
  

   supratemporal. 
  These 
  elements 
  are 
  pitted, 
  and 
  towards 
  their 
  

   margins 
  radiate 
  grooved. 
  These 
  sculpturings 
  grow 
  less 
  on 
  the 
  

   margins 
  of 
  the 
  supratemporal, 
  and 
  the 
  portions 
  of 
  the 
  surface 
  of 
  the 
  more 
  anterior 
  elements 
  remaining, 
  are 
  so 
  slightly 
  

   marked 
  as 
  to 
  give 
  the 
  impression 
  that 
  the 
  sculpturing 
  in 
  this 
  species 
  is 
  much 
  less 
  than 
  in 
  others 
  of 
  the 
  genus. 
  A 
  few 
  

   beaded 
  ridges 
  are 
  all 
  that 
  remain 
  on 
  the 
  parietals 
  and 
  postorbitals 
  ; 
  the 
  maxillaries 
  have 
  a 
  slightly 
  stronger 
  sculpture 
  

   seen 
  in 
  a 
  few 
  spots. 
  

  

  The 
  general 
  form 
  of 
  skull 
  is 
  elongate 
  behind, 
  and 
  much 
  shortened 
  in 
  front 
  of 
  the 
  orbits. 
  The 
  orbits 
  are 
  thus 
  

   altogether 
  in 
  front 
  of 
  a 
  line 
  equally 
  dividing 
  the 
  cranium 
  transversely, 
  while 
  in 
  the 
  D. 
  acadianum 
  they 
  are 
  in 
  the 
  

   middle 
  of 
  the 
  skull. 
  The 
  outline 
  of 
  the 
  muzzle 
  in 
  our 
  species 
  is 
  then 
  broad, 
  rounded, 
  as 
  in 
  the 
  Menopoma 
  alle- 
  

   gheniensis, 
  while 
  in 
  the 
  latter 
  it 
  is 
  ovate 
  and 
  produced. 
  It 
  therefore 
  resembles 
  also 
  in 
  its 
  proportions 
  the 
  genus 
  

   Hcrpetocephalus 
  Huxl, 
  from 
  the 
  Irish 
  Coal 
  Measures. 
  

  

  The 
  parietal 
  bones 
  extend 
  to 
  opposite 
  the 
  posterior 
  margins 
  of 
  the 
  orbits, 
  are 
  then 
  gradually 
  contracted, 
  and 
  

   form 
  an 
  acuminate 
  prolongation 
  on 
  each 
  side 
  the 
  wedge-shaped 
  frontals. 
  The 
  prefrontals 
  are 
  thickened 
  on 
  each 
  side 
  

   the 
  front, 
  behind 
  the 
  external 
  nares. 
  The 
  sutures 
  defining 
  the 
  frontals 
  anteriorly, 
  the 
  nasals, 
  and 
  the 
  premaxillarios 
  

   behind 
  cannot 
  be 
  made 
  out. 
  The 
  median 
  longitudinal 
  suture 
  is 
  a 
  marked 
  and 
  zigzag 
  one, 
  and 
  can 
  be 
  seen 
  as 
  far 
  

  

  