﻿VEETEBRATES. 
  149 
  

  

  So 
  far 
  as 
  relates 
  to 
  the 
  present 
  unique 
  example, 
  little 
  doubt 
  can 
  

   arise 
  as 
  to 
  its 
  specifically 
  distinct 
  character; 
  but 
  as 
  regards 
  the 
  forms 
  

   with 
  which 
  it 
  was 
  specifically 
  associated, 
  the 
  meagerness 
  of 
  the 
  ma- 
  

   terial 
  hardly 
  furnishes 
  a 
  clue 
  as 
  to 
  their 
  identity. 
  Thus 
  far, 
  the 
  

   Warsaw 
  limestone 
  has 
  afforded 
  only 
  a 
  few 
  fragmentary 
  remains 
  of 
  

   Deltodus, 
  some 
  of 
  which 
  certainly 
  are 
  very 
  intimately 
  related 
  to 
  the 
  

   Keokuk 
  species 
  D. 
  occidentalis 
  (maxillary 
  and 
  mandibular 
  posterior 
  

   forms) 
  ; 
  but 
  the 
  imperfect 
  state 
  of 
  preservation 
  of 
  these 
  specimens 
  

   offers 
  nothing 
  definite 
  bearing 
  on 
  their 
  specific 
  identity, 
  as 
  noticed 
  

   in 
  another 
  place. 
  We 
  are 
  satisfied 
  that 
  the 
  species 
  of 
  Deltodus 
  are, 
  

   in 
  some 
  instances 
  at 
  least, 
  extremely 
  intimately 
  related 
  to 
  one 
  

   another, 
  although 
  distinguishable 
  by 
  well-defined 
  peculiarities, 
  as 
  

   exhibited 
  by 
  ordinarily 
  well-preserved 
  examples. 
  However, 
  amongst 
  

   the 
  mass 
  of 
  material 
  — 
  like 
  that 
  including 
  D. 
  occidentalis 
  and 
  D. 
  un- 
  

   dulatus, 
  of 
  the 
  Keokuk 
  limestone 
  — 
  -it 
  is 
  impossible 
  to 
  recognize 
  the 
  

   specific 
  identity 
  of 
  the 
  fragmentary 
  individuals, 
  and 
  the 
  same 
  state 
  

   of 
  things 
  undoubtedly 
  obtains 
  in 
  respect 
  to 
  allied 
  representative 
  

   species. 
  

  

  Messrs. 
  Newberry 
  and 
  Worthen 
  have 
  described 
  (111. 
  Geol. 
  Surv. 
  IV, 
  

   p. 
  367, 
  PI. 
  IV, 
  f. 
  8) 
  a 
  maxillary 
  terminal 
  form 
  under 
  the 
  name 
  Del- 
  

   todus 
  Littoni, 
  reported 
  from 
  the 
  Carboniferous 
  limestone 
  of 
  Boone 
  

   county, 
  Missouri. 
  It 
  is 
  uncertain 
  whether 
  the 
  latter, 
  which 
  is 
  rep- 
  

   resented 
  by 
  an 
  unique 
  example, 
  was 
  derived 
  from 
  the 
  Warsaw 
  or 
  

   from 
  the 
  St. 
  Louis 
  formation, 
  both 
  of 
  these 
  formations, 
  as 
  also 
  the 
  

   Keokuk, 
  etc., 
  occurring 
  in 
  the 
  region 
  indicated; 
  however, 
  the 
  ap- 
  

   pearance 
  of 
  the 
  limestone 
  matrix 
  does 
  not 
  suggest 
  the 
  latter 
  horizon, 
  

   and 
  it 
  is 
  supposed 
  the 
  specimen 
  belongs 
  to 
  either 
  the 
  Warsaw 
  or 
  

   the 
  St. 
  Louis. 
  We 
  owe 
  to 
  the 
  courtesy 
  of 
  Dr. 
  Litton, 
  of 
  St. 
  Louis, 
  

   the 
  privilege 
  of 
  examining 
  the 
  type 
  specimen. 
  It 
  is 
  a 
  large, 
  much- 
  

   worn 
  tooth, 
  neither 
  border 
  of 
  which 
  is 
  sufficiently 
  complete 
  to 
  per- 
  

   mit 
  of 
  detail 
  comparison 
  with 
  allied 
  species. 
  The 
  relative 
  great 
  

   breadth 
  and 
  regular 
  convexity 
  of 
  the 
  coronal 
  ridge 
  and 
  apparently 
  

   narrow 
  posterior 
  alation, 
  offer 
  marked 
  contrast 
  to 
  the 
  prevalent 
  

   Keokuk 
  species 
  D. 
  occidentalis, 
  bearing 
  a 
  greater 
  resemblance 
  to 
  D. 
  

   undulatus, 
  especially, 
  compared 
  with 
  worn 
  examples 
  of 
  the 
  latter 
  

   species, 
  in 
  which 
  the 
  transverse 
  undulations 
  are 
  more 
  or 
  less 
  ob- 
  

   scured, 
  or 
  obsolete. 
  It 
  is 
  possible 
  the 
  narrow 
  median 
  tooth 
  de- 
  

   scribed 
  above 
  may 
  be 
  specifically 
  identical 
  with 
  the 
  latter 
  form, 
  in 
  

   which 
  event, 
  of 
  course, 
  the 
  name 
  by 
  which 
  it 
  is 
  here 
  designated 
  

   will 
  have 
  to 
  give 
  way 
  to 
  the 
  prior 
  term 
  bestowed 
  by 
  Messrs. 
  New- 
  

   berry 
  and 
  Worthen. 
  

  

  