﻿AND 
  KEL'TILIA 
  OF 
  NOETH 
  AMERICA. 
  7 
  

  

  and 
  the 
  cranium 
  is 
  very 
  differently 
  constructed 
  ; 
  in 
  Oestoc&phalus 
  it 
  is 
  much 
  as 
  in 
  

   Ptyonius 
  and 
  Lepterpeton. 
  The 
  characters 
  then 
  are 
  as 
  follows 
  : 
  

  

  Form 
  slender 
  and 
  snake-like; 
  caudal 
  vertebrae 
  with 
  dilated 
  and 
  sculptured 
  neural 
  

   and 
  haemal 
  spines. 
  Cranium 
  lanceolate. 
  Teeth 
  numerous, 
  of 
  nearly 
  equal 
  size. 
  No 
  

   pectoral 
  shields 
  ; 
  abdomen 
  protected 
  by 
  very 
  numerous 
  bristle-like 
  rods, 
  which 
  con- 
  

   verge 
  forwards 
  ; 
  scales 
  none. 
  A 
  pair 
  of 
  weak 
  posterior 
  limbs 
  ; 
  branchihyal 
  bones 
  

   present. 
  

  

  In 
  the 
  only 
  well-preserved 
  species, 
  the 
  cephalic 
  bones 
  exhibit 
  no 
  sculpture 
  from 
  

   the 
  parietal 
  region 
  forward. 
  The 
  angles 
  of 
  the 
  mandibles 
  are 
  prolonged 
  backwards 
  

   as 
  in 
  Apateon 
  and 
  the 
  Anura, 
  and 
  the 
  well 
  developed 
  ribs 
  commence 
  but 
  a 
  short 
  dis- 
  

   tance 
  behind 
  the 
  head. 
  The 
  vertebrae 
  are 
  slender 
  and 
  furnished 
  with 
  well 
  developed 
  

   diapophyses. 
  The 
  neural 
  spines 
  of 
  the 
  dorsal 
  vertebrae 
  in 
  O. 
  remex 
  are 
  flattened 
  and 
  

   antero-posteriorly 
  expanded 
  and 
  weakly 
  grooved 
  to 
  their 
  superior 
  margin. 
  

  

  The 
  character 
  which 
  separates 
  this 
  genera 
  from 
  Ptyonius 
  is 
  the 
  absence 
  of 
  the 
  

   three 
  usual 
  pectoral 
  shields. 
  In 
  two 
  specimens 
  the 
  pectoral 
  region 
  is 
  presented, 
  and 
  

   no 
  trace 
  of 
  the 
  shield 
  appears 
  ; 
  on 
  the 
  contrary 
  the 
  ventral 
  armature 
  of 
  bristles 
  or 
  

   rods 
  extends 
  to 
  the 
  head. 
  

  

  A 
  pair 
  of 
  symmetrical 
  bones, 
  whose 
  impressions 
  are 
  seen 
  posterior 
  to 
  the 
  occi- 
  

   pital 
  bone, 
  I 
  once 
  thought 
  might 
  belong 
  to 
  rudi 
  mental 
  limbs. 
  They 
  however 
  appear 
  

   to 
  be 
  the 
  elements 
  of 
  the 
  second 
  or 
  third 
  branchial 
  haemal 
  arch 
  ; 
  the 
  first 
  or 
  haemal 
  is 
  

   followed 
  by 
  a 
  second 
  element 
  which 
  is 
  probably 
  the 
  inferior 
  pleural 
  segment 
  of 
  the 
  

   arch. 
  A 
  third 
  piece 
  follows, 
  which 
  is 
  the 
  superior 
  pleural 
  element 
  of 
  the 
  same. 
  The 
  

   other 
  branchial 
  arches 
  are 
  lost, 
  but 
  some 
  impressions 
  are 
  visible. 
  

  

  Before 
  I 
  was 
  fully 
  acquainted 
  with 
  the 
  structure 
  in 
  this 
  genus, 
  I 
  referred 
  some 
  

   of 
  the 
  species 
  to 
  Sauropleura, 
  which 
  is 
  quite 
  distinct. 
  The 
  name 
  is 
  from 
  OioTor, 
  a 
  

   javelin 
  or 
  dart, 
  in 
  allusion 
  to 
  the 
  form 
  of 
  the 
  head. 
  My 
  friend, 
  Dr. 
  Benjamin 
  H. 
  

   Coates, 
  informs 
  me 
  that 
  this 
  Greek 
  word 
  retains 
  the 
  dieresis 
  in 
  composition, 
  and 
  

   should 
  not 
  be 
  spelled 
  with 
  a 
  dipthong. 
  

  

  I 
  am 
  acquainted 
  with 
  one 
  species 
  from 
  more 
  or 
  less 
  completely 
  preserved 
  skele- 
  

   tons, 
  with 
  portions 
  or 
  wholes 
  of 
  crania, 
  and 
  another 
  species 
  from 
  cranial 
  remains 
  alone. 
  

  

  They 
  may 
  be 
  distinguished 
  as 
  follows 
  : 
  

  

  I. 
  Vertebrae 
  elongate 
  ; 
  fan-like 
  caudal 
  processes 
  narrower. 
  Size 
  large; 
  mandi- 
  

   bular 
  teeth 
  of 
  unequal 
  lengths, 
  with 
  the 
  apices 
  turned 
  backwards. 
  O. 
  remex. 
  

  

  II. 
  Species 
  only 
  known 
  from 
  cranial 
  bones 
  with 
  teeth 
  ; 
  teeth 
  equal, 
  erect, 
  with 
  

   acute 
  conic 
  apices, 
  eleven 
  in 
  .005 
  m. 
  O. 
  kectidens. 
  

  

  