﻿VEETEBEATES. 
  153 
  

  

  The 
  present 
  species 
  is 
  represented 
  by 
  several 
  examples 
  of 
  the 
  

   mandibular 
  and 
  maxillary 
  posterior 
  forms, 
  whose 
  perfect 
  state 
  of 
  

   preservation 
  permits 
  of 
  detail 
  comparison 
  with 
  allied 
  species. 
  It 
  

   bears 
  most 
  intimate 
  relations 
  with 
  Deltodus 
  cinctulus 
  of 
  the 
  Warsaw 
  

   beds, 
  the 
  mandibular 
  teeth 
  being 
  chiefly 
  distinguishable 
  by 
  the 
  pro- 
  

   portionately 
  greater 
  breadth 
  of 
  the 
  principal 
  coronal 
  ridge, 
  narrower 
  

   posterior 
  wing, 
  and 
  the 
  more 
  numerous 
  transverse 
  furrows 
  and 
  

   ridges 
  ; 
  in 
  the 
  case 
  of 
  the 
  maxillary 
  posterior 
  form, 
  it 
  contrasts 
  

   with 
  that 
  of 
  the 
  above 
  species 
  in 
  the 
  relatively 
  more 
  prominent 
  

   coronal 
  ridge, 
  narrower 
  alation, 
  abrupt 
  deflection 
  in 
  the 
  course 
  of 
  

   the 
  inner 
  margin, 
  and 
  the 
  less 
  conspicuous, 
  narrow 
  transverse 
  

   undulations 
  traversing 
  the 
  coronal 
  region. 
  

  

  A 
  single 
  imperfect 
  specimen 
  of 
  a 
  minute 
  tooth 
  obtained 
  by 
  one 
  

   of 
  the 
  writers 
  at 
  St. 
  Louis, 
  is 
  provisionally 
  identified 
  with 
  the 
  narrow 
  

   median 
  form 
  of 
  the 
  mandible 
  of 
  the 
  present 
  species. 
  Partaking 
  in 
  

   an 
  intimate 
  degree 
  of 
  the 
  outline 
  and 
  coronal 
  contour 
  of 
  the 
  median 
  

   teeth 
  characteristic 
  of 
  the 
  genus, 
  as 
  it 
  is 
  now 
  interpreted, 
  its 
  small 
  

   size 
  suggests 
  relationships 
  with 
  the 
  specific 
  forms 
  above 
  alluded 
  to. 
  

   It 
  shows 
  the 
  prominent, 
  rounded 
  coronal 
  ridge, 
  narrow 
  alate 
  postero- 
  

   lateral 
  border, 
  and 
  the 
  still 
  narrower 
  and 
  shorter 
  articular 
  border 
  

   of 
  the 
  opposite 
  side, 
  but 
  the 
  mutilated 
  condition 
  of 
  the 
  specimen 
  

   does 
  not 
  disclose 
  the 
  distinctive 
  specific 
  characters 
  that 
  distinguish 
  

   it 
  from 
  congeneric 
  forms. 
  

  

  Geological 
  position 
  and 
  localities: 
  St. 
  Louis 
  formation 
  ; 
  Pella, 
  Iowa 
  ; 
  

   Alton, 
  Illinois 
  ; 
  St. 
  Louis, 
  Missouri. 
  

  

  Deltodus 
  intermedius, 
  St. 
  J. 
  and 
  W. 
  

  

  PI. 
  IX, 
  Fig. 
  14, 
  15. 
  

  

  Teeth 
  attain 
  medium 
  size. 
  Maxillary 
  posterior 
  form 
  sub-triangular 
  

   in 
  outline, 
  rather 
  strongly 
  arched 
  and 
  inrolled. 
  Antero-lateral 
  border 
  

   slightly 
  curved 
  sigmoidally, 
  articular 
  edge 
  very 
  narrow, 
  inbeveled 
  to 
  

   the 
  slightly 
  channeled, 
  shallow 
  basal 
  rim 
  ; 
  postero-lateral 
  border 
  

   converging 
  toward 
  inrolled 
  outer 
  margin 
  at 
  an 
  angle 
  of 
  35° 
  with 
  the 
  

   opposite 
  side, 
  somewhat 
  undulated, 
  the 
  relatively 
  thick 
  enamel 
  fold 
  

   sharply 
  inbeveled 
  to 
  the 
  channeled, 
  posteriorly 
  expanded 
  basal 
  rim, 
  

   which 
  is 
  rather 
  strongly 
  produced 
  at 
  the 
  subacute, 
  rounded 
  posterior 
  

   angle 
  ; 
  inner 
  margin 
  strongly 
  produced 
  inward 
  and 
  slightly 
  backward 
  

   from 
  the 
  very 
  obtuse 
  angle 
  at 
  the 
  junction 
  of 
  the 
  anterior 
  articular 
  

   border, 
  suddenly 
  deflected 
  nearly 
  at 
  right 
  angles 
  and 
  broadly 
  arched 
  

  

  