﻿22 
  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  GKOCEPHALA. 
  

  

  COLOSTEUS, 
  Cope. 
  

  

  This 
  genus 
  is 
  proposed 
  for 
  Ganocephala, 
  allied 
  to 
  Apateon 
  ( 
  Archegosaurus 
  ) 
  but 
  differ- 
  

   ing 
  as 
  follows 
  : 
  

  

  There 
  are 
  no 
  traces 
  of 
  vertebral 
  centra 
  or 
  spines, 
  or 
  of 
  ribs, 
  in 
  portions 
  of 
  six 
  individ- 
  

   uals 
  preserved. 
  No 
  sclerotic 
  bones 
  can 
  be 
  found 
  in 
  one 
  cranium 
  partially 
  preserved. 
  

   There 
  appears 
  to 
  be 
  two 
  pairs 
  of 
  very 
  short 
  limbs. 
  The 
  usual 
  three 
  sculptured 
  pectoral 
  

   bones 
  are 
  present, 
  consisting 
  of 
  a 
  rhombic 
  medial, 
  and 
  a 
  pair 
  of 
  half 
  rhomboid 
  laterals. 
  

   The 
  abdominal 
  region 
  is 
  protected 
  by 
  series 
  of 
  scales 
  which 
  extend 
  obliquely 
  forwards 
  to 
  

   the 
  medial 
  line, 
  where 
  they 
  meet, 
  forming 
  chevrons. 
  They 
  are 
  closely 
  approximated, 
  

   and 
  are 
  composed 
  of 
  rhomboidal 
  scales 
  which 
  have 
  a 
  convex 
  external 
  and 
  internal 
  face, 
  

   in 
  transverse 
  section, 
  and 
  which 
  overlap 
  at 
  the 
  extremities, 
  and 
  are 
  in 
  contact 
  by 
  faces 
  

   which 
  are 
  oblique 
  in 
  both 
  the 
  longitudinal 
  and 
  transverse 
  directions. 
  

  

  The 
  exact 
  form 
  of 
  the 
  muzzle 
  cannot 
  be 
  made 
  out. 
  It 
  is, 
  however, 
  not 
  elongate, 
  nor 
  

   yet 
  of 
  the 
  broad 
  rounded 
  form 
  of 
  Pelion. 
  Several 
  teeth 
  are 
  preserved. 
  There 
  are 
  

   two 
  kinds, 
  which 
  occupy 
  the 
  margins 
  of 
  the 
  maxillary 
  and 
  dentary 
  bones. 
  The 
  

   anterior 
  teeth 
  appear 
  to 
  be 
  longer 
  than 
  the 
  posterior, 
  though 
  the 
  latter 
  are 
  mostly 
  

   broken 
  off. 
  Most 
  of 
  the 
  teeth 
  are 
  coarsely 
  incised 
  sulcate 
  for 
  perhaps 
  their 
  basal 
  half. 
  

   Two 
  long 
  teeth 
  behind 
  their 
  distal 
  extremity 
  of 
  the 
  dentale, 
  are 
  on 
  the 
  other 
  hand 
  Aery 
  

   finely 
  and 
  sharply 
  striate 
  for 
  their 
  basal 
  half; 
  the 
  tip 
  is 
  subcylindric, 
  and 
  very 
  prolonged 
  

   and 
  acute. 
  A 
  small, 
  dagger-shaped 
  tooth 
  near 
  the 
  base 
  of 
  one 
  of 
  the 
  posterior, 
  may 
  be- 
  

   long 
  to 
  the 
  successional, 
  or 
  to 
  a 
  small 
  outer 
  series. 
  A 
  series, 
  of 
  four 
  elevated 
  tooth 
  bases, 
  

   with 
  a 
  broken 
  crown, 
  of 
  much 
  smaller 
  size 
  than 
  those 
  of 
  the 
  jaws 
  belongs 
  to 
  the 
  vomerine 
  

   or 
  a 
  palatine 
  series. 
  The 
  row 
  is 
  single 
  and 
  uniform. 
  

  

  The 
  superior 
  face 
  of 
  the 
  cranium 
  is 
  injured, 
  but 
  the 
  component 
  bones 
  appear 
  to 
  have 
  

   possessed 
  a 
  radiating 
  sculpture 
  of 
  no 
  great 
  distinctness. 
  

  

  The 
  form 
  of 
  the 
  body 
  seems 
  to 
  have 
  been 
  long 
  and 
  fish-like, 
  with 
  little 
  contraction 
  near 
  

   the 
  limbs. 
  Caudal 
  extremity 
  is 
  not 
  preserved. 
  There 
  were 
  probably 
  two 
  pairs 
  of 
  very 
  

   weak 
  limbs, 
  of 
  which 
  three 
  metacarpals 
  of 
  the 
  anterior 
  are 
  preserved. 
  A 
  narrow 
  longi- 
  

   tudinal 
  bone 
  extends 
  posteriorly 
  from 
  the 
  lateral 
  pectoral 
  bone. 
  Its 
  extremity 
  is 
  broken, 
  

   but 
  a 
  Hat, 
  narrow, 
  longitudinal 
  bone, 
  with 
  a 
  dilated 
  extremity 
  curved 
  outwards, 
  may 
  be- 
  

   long 
  to 
  it, 
  or 
  be 
  the 
  humerus. 
  I 
  find 
  no 
  distinct 
  traces 
  of 
  branchial 
  arches. 
  

  

  The 
  affinities 
  are 
  thus 
  obviously 
  to 
  Apateon, 
  and 
  it 
  is 
  not 
  beyond 
  possibility 
  that 
  future 
  

   investigations 
  may 
  prove 
  it 
  is 
  the 
  same, 
  though 
  this 
  is 
  not 
  probable 
  at 
  present. 
  

  

  Portions 
  of 
  seven 
  individuals 
  of 
  one 
  species, 
  and 
  of 
  one 
  individual 
  of 
  another, 
  were 
  

   discovered 
  by 
  Prof. 
  John 
  S. 
  Newberry 
  at 
  Linton, 
  Ohio. 
  They 
  differ 
  as 
  follows: 
  

  

  