﻿AND 
  AYES 
  OF 
  NORTH 
  AMERICA. 
  

  

  LABYRINTHODONTIA 
  Vera. 
  

  

  Vertebral 
  centra 
  osseous; 
  no 
  branchial 
  hyoids; 
  teeth 
  with 
  much 
  inflected 
  enamel, 
  

   anchylosed 
  in 
  shallow 
  alveoli. 
  Occipital 
  condyles. 
  

   Our 
  knowledge 
  of 
  these 
  forms 
  is 
  as 
  yet 
  in 
  many 
  cases 
  too 
  incomplete, 
  to 
  enable 
  us 
  to 
  

   assert 
  positively 
  as 
  to 
  the 
  structure 
  and 
  position 
  of 
  the 
  teeth, 
  and 
  the 
  preceding 
  arrange- 
  

   ment 
  is 
  designed 
  to 
  shadow 
  out 
  the 
  true 
  system, 
  rather 
  than 
  to 
  define 
  the 
  groups 
  exactly. 
  

   They 
  may 
  be 
  arranged 
  further 
  in 
  the 
  following 
  manner, 
  with 
  reference 
  to 
  the 
  dermal 
  

   armature. 
  

  

  I. 
  Three 
  large 
  pectoral 
  plates. 
  

  

  « 
  Abdomen 
  with 
  numerous 
  short 
  or 
  long 
  bony 
  scales 
  in 
  close 
  series. 
  

   / 
  J 
  A 
  bony 
  sclerotic 
  ring. 
  

   Teeth 
  simple. 
  Xenorluteltia. 
  Ampliibamus. 
  

  

  Teeth 
  complex. 
  Ganocejphala. 
  Archegosaurus. 
  

  

  i 
  1 
  ? 
  No 
  bony 
  ring. 
  

  

  C'olosteus 
  n. 
  gen. 
  

   rholidogaster. 
  

   Pteroplax. 
  

   Microcauria. 
  ( 
  Vratcrpeton. 
  

  

  Urocordylus. 
  

  

  II. 
  No 
  pectoral 
  osseous 
  shields. 
  

  

  " 
  Abdomen 
  with 
  oblique 
  series 
  of 
  long 
  or 
  short 
  scales. 
  

  

  Microsa 
  aria. 
  Sauropleura. 
  

  

  (Estocephalus. 
  

   Lepterpeton. 
  

   Ophiderpeton. 
  

   Hylonomus. 
  

   Dendrerpeton. 
  

  

  «« 
  No 
  abdominal 
  scales 
  known. 
  

  

  Pelion. 
  

   Molgophis. 
  

  

  XENOEHACHIA. 
  

  

  This 
  order 
  I 
  proposed 
  for 
  the 
  reception 
  of 
  the 
  genus 
  Amphibamus 
  Cope, 
  in 
  1865. 
  I 
  

   proposed 
  to 
  regard 
  as 
  one 
  of 
  its 
  characters, 
  the 
  existence 
  of 
  opisthoceelian 
  vertebra?. 
  Such 
  

   impressions 
  were 
  observed 
  in 
  the 
  matrix 
  in 
  whicli 
  the 
  fossil 
  was 
  preserved, 
  as 
  to 
  induce 
  a 
  

  

  