﻿VERTEBRATES. 
  81 
  

  

  species 
  noticed 
  respectively 
  from 
  the 
  St. 
  Louis 
  and 
  Chester 
  forma- 
  

   tions, 
  as 
  will 
  be 
  remarked 
  further 
  on. 
  The 
  earliest 
  representative 
  

   occurs 
  in 
  the 
  upper 
  horizon 
  of 
  the 
  Kinderhook 
  formation, 
  the 
  Upper 
  

   Burlington, 
  St. 
  Louis 
  and 
  Chester 
  each 
  contributing 
  representative 
  

   forms, 
  while 
  a 
  single 
  form 
  from 
  the 
  Upper 
  Coal 
  Measures, 
  and 
  one 
  

   from 
  the 
  Lower 
  Coal 
  Measures, 
  are 
  with 
  doubt 
  here 
  referred. 
  The 
  

   Kinderhook 
  and 
  Upper 
  Burlington 
  afford 
  the 
  typical 
  representatives, 
  

   being 
  represented 
  by 
  examples 
  which 
  it 
  is 
  difficult 
  to 
  believe 
  ever 
  

   possessed 
  the 
  distinctive 
  characters 
  essentially 
  attributed 
  to 
  Deltop- 
  

   tychius. 
  We 
  owe 
  to 
  the 
  kindness 
  of 
  Lord 
  Enniskillen 
  opportunity 
  to 
  

   compare, 
  from 
  drawings, 
  a 
  magnificent 
  tooth 
  derived 
  from 
  the 
  Car- 
  

   boniferous 
  limestone 
  of 
  Oreton, 
  in 
  Shropshire, 
  England, 
  and 
  belong- 
  

   ing 
  to 
  the 
  museum 
  at 
  Florence 
  Court, 
  Ireland. 
  The 
  latter 
  tooth 
  

   shows 
  a 
  large 
  example, 
  above 
  four 
  inches 
  in 
  its 
  greatest 
  diameter, 
  

   and 
  of 
  proportionate 
  dimensions, 
  of 
  the 
  maxillary 
  posterior 
  form. 
  

   So 
  far 
  as 
  it 
  is 
  possible 
  to 
  judge 
  from 
  the 
  drawings, 
  it 
  possesses 
  pre- 
  

   cisely 
  the 
  coronal 
  contour 
  characteristic 
  of 
  the 
  teeth 
  of 
  the 
  corres- 
  

   ponding 
  form 
  noticed 
  in 
  the 
  following 
  pages. 
  The 
  resemblances 
  in 
  

   common 
  between 
  the 
  Shropshire 
  and 
  the 
  Kinderhook 
  teeth 
  are 
  

   especially 
  pronounced, 
  neither 
  the 
  one 
  nor 
  the 
  other 
  would 
  be 
  mis- 
  

   taken 
  for 
  a 
  typical 
  Deltoptychius. 
  In 
  both 
  examples 
  the 
  posterior 
  

   prominence 
  is 
  obscurely 
  defined 
  from 
  the 
  plain 
  anterior 
  region, 
  

   which 
  shows 
  not 
  a 
  trace 
  of 
  secondary 
  lobe. 
  The 
  genus 
  may 
  also 
  

   include 
  the 
  tooth 
  described 
  by 
  Dr. 
  L. 
  de 
  Koninck 
  1 
  under 
  the 
  name 
  

   Streblodus 
  tenerrimus, 
  from 
  the 
  Lower 
  Carboniferous 
  deposits 
  of 
  Tour- 
  

   nay, 
  Belgium. 
  

  

  Again, 
  if 
  the 
  evidence 
  be 
  fairly 
  admissible, 
  the 
  forms 
  here 
  especi- 
  

   ally 
  referred 
  to, 
  offer 
  some 
  most 
  interesting 
  suggestions 
  bearing 
  on 
  

   the 
  derivation 
  of 
  allied 
  and 
  coexisting 
  generic 
  forms. 
  That 
  referred 
  

   to 
  under 
  the 
  name 
  Vaticinodus 
  vetustus, 
  from 
  the 
  Kinderhook, 
  rep- 
  

   resents 
  the 
  earliest 
  species 
  not 
  only 
  of 
  this 
  particular 
  group, 
  but 
  

   also 
  of 
  typical 
  Cochliodonts. 
  Passing 
  up 
  into 
  the 
  Upper 
  Burlington, 
  

   next 
  is 
  met 
  with 
  an 
  apparently 
  congeneric 
  form 
  V. 
  discrepans. 
  Dur- 
  

   ing 
  the 
  latter 
  epoch 
  Chitonodus, 
  the 
  immediate 
  precursor 
  of 
  Cochlio- 
  

   dus, 
  was 
  introduced, 
  and 
  also 
  Deltoptychius 
  and 
  Stenopterodus. 
  The 
  

   latter 
  is 
  plainly 
  a 
  somewhat 
  more 
  pronounced 
  differentiation, 
  while 
  

   Deltoptychius 
  holds 
  an 
  intermediate 
  place 
  between 
  the 
  primal 
  groups 
  

   and 
  Stenopterodus. 
  

  

  (Note.) 
  » 
  Faune 
  calcaire 
  Carbonifcre 
  de 
  la 
  Belgique, 
  II, 
  p. 
  55, 
  P. 
  VI, 
  f. 
  13. 
  

  

  