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  Ittfl 
  

  

  y 
  

  

  PLATE 
  VI. 
  

  

  Page. 
  

  

  Chitonodus 
  lieatus, 
  St. 
  J. 
  and 
  W 
  119 
  

  

  Ji 
  Fig. 
  1 
  a. 
  Maxillary 
  posterior 
  tooth, 
  right 
  ramus, 
  view 
  from 
  above 
  of 
  an 
  imperfect 
  ex- 
  

   ample, 
  posterior 
  extremity 
  restored 
  in 
  outline; 
  1 
  b, 
  do., 
  from 
  the 
  inner 
  

   margin. 
  St. 
  Louis 
  limestone; 
  Alton, 
  111. 
  

  

  Chitonodus 
  antiquus, 
  St. 
  J. 
  andW 
  116 
  

  

  Pig. 
  2a. 
  Mandibular 
  posterior 
  tooth, 
  left 
  ramus, 
  view 
  from 
  above, 
  outline 
  partially 
  

   restored; 
  2 
  b, 
  do., 
  transverse 
  profile 
  from 
  inner 
  margin; 
  2 
  c, 
  do., 
  outer 
  

   inrolled 
  margin; 
  2d, 
  do., 
  from 
  the 
  antero-lateral 
  border. 
  Lower 
  Bur- 
  

   lington, 
  Iowa. 
  Prof. 
  Worthen. 
  

  

  Chitonodus 
  Speingeki, 
  St. 
  J. 
  and 
  W 
  112 
  

  

  \%. 
  < 
  \ 
  < 
  \ 
  V 
  Pig- 
  3 
  a 
  - 
  Maxillary 
  posterior 
  tooth, 
  left 
  ramus, 
  view 
  from 
  above 
  of 
  a 
  worn 
  example, 
  

   outline 
  partially 
  restored; 
  3 
  &, 
  do., 
  from 
  inner 
  margin; 
  3 
  c, 
  do., 
  outer 
  in- 
  

   rolled 
  margin; 
  3 
  d, 
  do., 
  from 
  the 
  anterior 
  border, 
  foreshortened. 
  Upper 
  

   Burlington; 
  Augusta, 
  Iowa. 
  Mr. 
  "Wachsmuth. 
  

   Pig. 
  4 
  a. 
  Same 
  form, 
  right 
  ramus, 
  a 
  worn 
  specimen, 
  seen 
  from 
  above; 
  4 
  b, 
  do., 
  inner 
  

   margin; 
  4 
  c, 
  do., 
  outer 
  inrolled 
  margin; 
  id, 
  do., 
  from 
  anterior 
  border, 
  

   foreshortened. 
  Upper 
  Burlington; 
  Louisa 
  county, 
  Iowa. 
  Mr. 
  Springer. 
  

   fi 
  ^_ 
  / 
  Pig. 
  5 
  a. 
  Mandibular 
  posterior 
  tooth, 
  left 
  ramus, 
  view 
  from 
  above; 
  5 
  b, 
  do., 
  inner 
  

   margin; 
  5 
  c, 
  do., 
  from 
  antero-lateral 
  border; 
  a 
  worn 
  example, 
  showing 
  

   merely 
  a 
  trace 
  of 
  transverse 
  imbrications. 
  Upper 
  Burlington; 
  Augusta, 
  

   Iowa. 
  0. 
  St. 
  John. 
  

   £,3 
  / 
  Pig. 
  6 
  a. 
  A 
  worn, 
  medium-size 
  example 
  of 
  the 
  same 
  form, 
  seen 
  from 
  above; 
  6 
  b, 
  do., 
  

   inner 
  margin; 
  6 
  c, 
  do., 
  outer 
  inrolled 
  margin; 
  6 
  d, 
  do., 
  from 
  the 
  anterior 
  

   border. 
  Upper 
  Burlington; 
  Augusta, 
  Iowa. 
  Mr. 
  Springer. 
  

   \/ 
  Fig. 
  7 
  a. 
  Mandibular 
  median 
  tooth, 
  left 
  ramus, 
  a 
  worn 
  specimen, 
  seen 
  from 
  above, 
  

   outer 
  extremity 
  restored 
  in 
  outline; 
  7 
  b, 
  do., 
  inner 
  margin, 
  transverse 
  

   profile; 
  7 
  c, 
  do., 
  outer 
  margin; 
  7 
  d, 
  do., 
  from 
  antero-lateral 
  border; 
  7 
  c, 
  

   do., 
  postero-lateral 
  border. 
  Upper 
  Burlington; 
  Louisa 
  county, 
  Iowa. 
  

   Mr. 
  Springer. 
  

   V 
  Pig. 
  8 
  a, 
  b, 
  c, 
  d, 
  e. 
  Similar 
  views 
  of 
  a 
  more 
  prominently 
  rigid, 
  worn 
  example 
  of 
  the 
  

   same 
  form, 
  outline 
  partially 
  restored. 
  Upper 
  Burlington; 
  Augusta, 
  

   Iowa. 
  

   y/ 
  Pig. 
  9 
  a. 
  Maxillary 
  posterior 
  tooth, 
  left 
  ramus, 
  a 
  medium-size 
  example, 
  preserving 
  

   |JL^V 
  the 
  transverse 
  imbrications 
  over 
  a 
  portion 
  of 
  the 
  anterior 
  neck, 
  seen 
  

  

  from 
  above, 
  outline 
  partially 
  restored; 
  9 
  6, 
  do,, 
  inner 
  margin, 
  trans- 
  

   verse 
  profile; 
  9 
  c, 
  do., 
  from 
  anterior 
  border; 
  9 
  d, 
  from 
  posterior 
  ex- 
  

   ftremity. 
  Upper 
  Burlington; 
  Louisa 
  county, 
  Iowa. 
  0. 
  St. 
  John. 
  

   Fig. 
  10 
  a. 
  A 
  large, 
  robust 
  example 
  of 
  the 
  same 
  form, 
  from 
  above, 
  partially 
  restored 
  

   in 
  outline; 
  10 
  b, 
  do., 
  inner 
  margin; 
  10 
  c, 
  do., 
  outer 
  inrolled 
  margin; 
  10 
  d, 
  

   do., 
  from 
  anterior 
  border, 
  foreshortened. 
  Upper 
  Burlington; 
  Augusta, 
  

   Iowa. 
  

   Pig. 
  11 
  a. 
  A 
  similar 
  example 
  of 
  the 
  same 
  form, 
  seen 
  from 
  above, 
  outline 
  restored. 
  

   Upper 
  Burlington; 
  Pleasant 
  Grove, 
  Iowa. 
  Prof. 
  Worthen. 
  

   -^ 
  . 
  — 
  -Fig. 
  12 
  a. 
  Mandibular 
  posterior 
  tooth, 
  right 
  ramus, 
  showing 
  transverse 
  imbrications, 
  

   1 
  3 
  view 
  from 
  above, 
  outline 
  restored. 
  Upper 
  Burlington; 
  Louisa 
  county, 
  

  

  Iowa. 
  O. 
  St. 
  John. 
  

  

  13 
  

  

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