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  THE 
  EXTINCT 
  BATRACHIA, 
  EEPTILIA 
  

  

  COMPARATIVE 
  OBSERVATIONS. 
  

  

  The 
  study 
  of 
  the 
  early 
  extinct 
  vertebrata 
  of 
  this 
  country 
  possesses 
  three 
  points 
  of 
  in- 
  

   terest, 
  to 
  which 
  the 
  attention 
  of 
  students 
  has 
  been 
  drawn. 
  First: 
  the 
  period 
  at 
  which 
  

   given 
  types 
  of 
  life 
  have 
  appeared 
  on 
  the 
  earth; 
  second: 
  whether 
  such 
  types 
  present 
  ab- 
  

   rupt 
  beginning 
  and 
  close, 
  or 
  exhibit 
  a 
  connection 
  with 
  others 
  by 
  intervening 
  and 
  only 
  

   partly 
  subordinate 
  forms 
  ; 
  third 
  : 
  whether 
  the 
  periods 
  of 
  existence 
  of 
  given 
  types 
  were 
  

   synchronous 
  in 
  different 
  regions 
  of 
  the 
  earth. 
  

  

  With 
  reference 
  to 
  the 
  second 
  point, 
  it 
  may 
  be 
  said, 
  that, 
  although 
  investigations 
  in 
  the 
  

   field 
  in 
  question 
  bring 
  to 
  light 
  forms 
  combining 
  peculiarities 
  once 
  supposed 
  to 
  exist 
  only 
  

   in 
  distinct 
  types, 
  the 
  primary 
  divisions 
  as 
  herein 
  denned 
  have 
  not 
  yet 
  been 
  found 
  

   to 
  be 
  connected 
  by 
  forms 
  not 
  referable 
  to 
  any 
  of 
  them. 
  If 
  we 
  suppose 
  that 
  such 
  have 
  ex- 
  

   isted, 
  it 
  is 
  only 
  by 
  the 
  analogy 
  of 
  forms 
  discovered 
  to 
  be 
  intermediate 
  on 
  a 
  lower 
  grade 
  of 
  

   characters. 
  

  

  The 
  period 
  of 
  commencement 
  of 
  the 
  Reptilian 
  Orders 
  has 
  been 
  generally 
  believed 
  to 
  

   be 
  that 
  of 
  the 
  Permian. 
  No 
  reptile 
  has 
  been 
  discovered 
  in 
  and 
  below 
  the 
  Coal 
  Measures 
  

   in 
  the 
  old 
  world, 
  and 
  nothing 
  has 
  been 
  found 
  in 
  the 
  new 
  to 
  invalidate 
  this 
  general 
  state- 
  

   ment. 
  Batrachia 
  have 
  left 
  their 
  tracks 
  in 
  the 
  Subcarboniferous 
  ; 
  below 
  this 
  they 
  are 
  not 
  

   known; 
  their 
  remains 
  first 
  appear 
  in 
  "the 
  Carboniferous. 
  Birds 
  first 
  appear 
  in 
  the 
  Cre- 
  

   taceous, 
  though 
  they 
  have 
  been 
  chiefly 
  found 
  in 
  Eocene 
  and 
  Miocene 
  strata. 
  

  

  With 
  regard 
  to 
  the 
  relative 
  abundance 
  of 
  these 
  types 
  in 
  the 
  two 
  continents, 
  it 
  may 
  be 
  

   observed, 
  that 
  with 
  present 
  knowledge 
  they 
  appear 
  to 
  be 
  nearly 
  similarly 
  developed, 
  with 
  

   the 
  following 
  exceptions 
  : 
  The 
  American 
  formations 
  are 
  very 
  poor 
  in 
  Ichthyopterygia 
  and 
  

   Pterosauria, 
  orders 
  greatly 
  developed 
  in 
  Europe; 
  while 
  they 
  contain 
  abundant 
  remains 
  of 
  

   Pythonomorpha, 
  which 
  is 
  represented 
  in 
  European 
  beds 
  by 
  but 
  few 
  species. 
  The 
  subject 
  

   is, 
  however, 
  in 
  its 
  infancy. 
  

  

  With 
  respect 
  to 
  the 
  synchronism 
  of 
  the 
  Reptilian 
  fauna? 
  here 
  alluded 
  to, 
  the 
  knowledge 
  

   of 
  the 
  subject 
  is 
  not 
  sufficient 
  to 
  furnish 
  basis 
  for 
  an 
  opinion, 
  but 
  I 
  have 
  elsewhere 
  at- 
  

   tempted 
  to 
  show 
  that 
  similar 
  faunas 
  were 
  quite 
  as 
  likely 
  to 
  prove 
  successional, 
  and 
  succes- 
  

   sional 
  fauna? 
  synchronous, 
  as 
  the 
  reverse. 
  (See 
  Origin 
  of 
  Genera.) 
  

  

  As 
  to 
  the 
  relations 
  of 
  times 
  of 
  appearance 
  in 
  the 
  continents 
  of 
  Europe 
  and 
  North 
  

   America, 
  we 
  know 
  too 
  few 
  species 
  to 
  be 
  able 
  to 
  make 
  more 
  than 
  a 
  comparison 
  which 
  time 
  

   may 
  invalidate. 
  Of 
  the 
  periods 
  of 
  predominance 
  of 
  types 
  a 
  little 
  more 
  may 
  be 
  said. 
  

   Thus, 
  both 
  continents 
  alike 
  present 
  a 
  majority 
  of 
  the 
  smaller 
  Stegocephalous 
  Batrachia 
  

   during 
  Carboniferous 
  time, 
  and 
  of 
  the 
  larger 
  Labyrinthodonts 
  during 
  Triassic 
  time. 
  

  

  Our 
  only 
  Ichthyopterygia 
  (not 
  reckoning 
  Eosaurus) 
  appear 
  in 
  supposed 
  Triassic 
  beds: 
  

   those 
  of 
  the 
  old 
  world 
  do 
  not 
  occur 
  before 
  the 
  Jurassic 
  (one 
  is 
  noted 
  from 
  the 
  German 
  

   Trias). 
  The 
  old 
  world 
  Sauropterygia 
  greatly 
  predominate 
  in 
  the 
  Jurassic, 
  though 
  a 
  few 
  

  

  