﻿VEETEBEATES. 
  91 
  

  

  The 
  various 
  forms 
  of 
  teeth 
  constituting 
  the 
  dentition 
  of 
  Deltopty- 
  

   chius 
  have 
  been 
  in 
  all 
  cases 
  recognized 
  from 
  isolated 
  detached 
  

   specimens, 
  save 
  in 
  the 
  instance 
  of 
  the 
  maxillary 
  posterior 
  and 
  median 
  

   serial 
  teeth. 
  In 
  the 
  latter 
  we 
  have 
  authentic 
  evidence 
  of 
  specific 
  

   . 
  identity, 
  in 
  the 
  discovery 
  by 
  Mr. 
  Wachsmuth 
  of 
  a 
  specimen 
  show- 
  

   £«./•*<*? 
  / 
  ing 
  the 
  teeth 
  in 
  actual 
  - 
  aiatcrial 
  - 
  juxta-position. 
  "Wherever 
  the 
  one 
  

   ' 
  form 
  occurs 
  there 
  also 
  is 
  found 
  the 
  other/, 
  and 
  taking 
  this 
  fact 
  into 
  

   consideration 
  and 
  what 
  is 
  known 
  of 
  the 
  various 
  forms 
  of 
  teeth 
  be- 
  

   longing 
  to 
  the 
  genera 
  Cochliodus, 
  Orthopleurodus, 
  etc., 
  the 
  association 
  

   here 
  conjectured 
  seems 
  to 
  be 
  amply 
  warranted. 
  The 
  genus 
  as 
  here 
  

   defined 
  bears 
  intimate 
  relationship 
  with 
  Cochliodus 
  and 
  Chitonodus, 
  

   holding 
  an 
  intermediate 
  position 
  between 
  the 
  latter 
  and 
  Vaticinodus 
  

   and 
  Stenopterodus. 
  It 
  is, 
  however, 
  distinguished 
  from 
  the 
  former 
  by 
  

   peculiarities 
  in 
  the 
  coronal 
  contour 
  of 
  the 
  maxillary 
  posterior 
  teeth, 
  

   and 
  the 
  greater 
  obliquity, 
  cuneate 
  outline 
  of 
  the 
  mandibular 
  posterior 
  

   form, 
  but 
  chiefly 
  in 
  the 
  character 
  of 
  the 
  enameled 
  abrupt 
  antero- 
  

   lateral 
  border 
  of 
  the 
  latter 
  form, 
  which 
  in 
  Cochliodus 
  presents 
  a 
  

   narrow 
  fold 
  precisely 
  like 
  that 
  along 
  the 
  postero-lateral 
  border, 
  also 
  

   as 
  occurs 
  in 
  either 
  lateral 
  border 
  of 
  the 
  maxillary 
  posterior 
  form. 
  

   This, 
  in 
  view 
  of 
  the 
  uniformity 
  of 
  the 
  articular 
  borders 
  in 
  the 
  vari-4Ji£* 
  

   forms 
  of 
  Cochliodus, 
  Chitonodus 
  and 
  their 
  intimate 
  allies, 
  might 
  be 
  

   regarded 
  as 
  inconsistent 
  with 
  the 
  conjectured 
  association 
  of 
  forms 
  

   in 
  the 
  present 
  generic 
  group 
  of 
  teeth. 
  But 
  after 
  all 
  it 
  seems 
  in 
  

   some 
  sort 
  to 
  foreshadow 
  or 
  form 
  a 
  transition 
  from 
  the 
  true 
  Cochlio- 
  

   dus 
  type 
  to 
  that 
  of 
  Pcecilodus, 
  the 
  mandibular 
  posterior 
  form 
  of 
  

   which 
  possesses 
  much 
  the 
  same 
  character 
  of 
  steep 
  enameled 
  antero- 
  

   lateral 
  border 
  as 
  obtains 
  in 
  the 
  homologous 
  form 
  of 
  the 
  present 
  

   genus 
  ; 
  in 
  both 
  of 
  the 
  latter 
  genera 
  the 
  articular 
  border 
  of 
  the 
  

   opposed 
  maxillary 
  form 
  partakes 
  still 
  to 
  a 
  most 
  intimate 
  degree 
  of 
  

   the 
  character 
  of 
  typical 
  Cochliodus.. 
  

  

  The 
  genus 
  is 
  apparently 
  confined 
  to 
  the 
  measures 
  of 
  the 
  Lower 
  

   Carboniferous 
  period, 
  representative 
  species 
  occurring 
  in 
  each 
  of 
  the 
  

   successive 
  formations 
  beginning 
  with 
  the 
  Upper 
  Burlington, 
  and 
  

   includes 
  the 
  form 
  described 
  by 
  Dr. 
  Leidy 
  under 
  the 
  name 
  Coch- 
  

   liodus 
  nitidus, 
  of 
  the 
  Chester 
  formation. 
  1 
  

  

  According 
  to 
  the 
  above 
  interpretation 
  of 
  the 
  facts, 
  the 
  genus 
  pos- 
  

   sesses 
  precisely 
  similar 
  diagnostic 
  terms 
  distinguishing 
  the 
  form 
  

   referred 
  by 
  authors 
  to 
  the 
  "anterior" 
  tooth 
  of 
  Deltoptychius 
  acutus, 
  

  

  trails. 
  Am. 
  Phil. 
  Soc„ 
  vol. 
  xi, 
  p. 
  87, 
  PI. 
  v, 
  f. 
  2. 
  

  

  