﻿IV 
  

  

  v./ 
  

  

  

  PLATE 
  XVI. 
  ■ 
  

  

  Page. 
  

   Fig.1-4 
  Psammodus 
  plenus, 
  St. 
  J. 
  and 
  W 
  , 
  21$ 
  

  

  \ 
  la. 
  Mandibular 
  tooth, 
  view 
  from 
  above; 
  1 
  b, 
  do., 
  from 
  the 
  articular 
  border; 
  1 
  c, 
  

   do., 
  exterior 
  border; 
  1 
  d, 
  do., 
  posterior 
  margin; 
  1 
  e, 
  do., 
  anterior 
  margin; 
  

   /, 
  do., 
  inferior 
  surface. 
  St. 
  Louis 
  limestone; 
  Alton, 
  Ills. 
  Mr. 
  Yan 
  Home. 
  

  

  2 
  a. 
  A 
  similar 
  example 
  of 
  the 
  same 
  form, 
  from 
  above, 
  outline 
  partially 
  restored; 
  

   2 
  b. 
  do., 
  inferior 
  surface; 
  2 
  c, 
  do., 
  showing 
  the 
  channeled 
  exterior 
  border. 
  

   St. 
  Louis 
  limestone; 
  Monroe 
  county, 
  Ills. 
  Prof. 
  Worthen. 
  

  

  3(i,5, 
  A 
  nearly 
  perfect 
  specimen 
  of 
  the 
  same 
  form, 
  view 
  from 
  above 
  and 
  the 
  ar- 
  

   ticular 
  border, 
  showing 
  a 
  faint 
  marginal 
  sulcation 
  round 
  the 
  articular, 
  

   posterior 
  and 
  anterior 
  margins 
  of 
  the 
  crown. 
  St. 
  Louis 
  limestone; 
  Alton. 
  

   Ills. 
  Mr. 
  Van 
  Home. 
  

  

  4 
  a. 
  View 
  from 
  above 
  of 
  a 
  fragment 
  of 
  a 
  very 
  large 
  maxillary 
  tooth, 
  partially 
  

   restored 
  in 
  outline; 
  4 
  b, 
  do., 
  from 
  the 
  posterior 
  margin; 
  4 
  c, 
  do., 
  articular 
  

   inner 
  border. 
  St. 
  Louis 
  limestone; 
  Alton. 
  Mr. 
  Alex. 
  Butters. 
  

  

  