﻿VEETEBEATES. 
  159 
  

  

  mit. 
  The 
  anterolateral 
  and 
  postero-lateral 
  borders 
  are 
  marked 
  as 
  

   in 
  Deltodus. 
  The 
  coronal 
  fold 
  of 
  the 
  articular 
  border, 
  perhaps, 
  more 
  

   rounded 
  and 
  relatively 
  narrower 
  than 
  that 
  of 
  the 
  postero-lateral 
  

   border. 
  

  

  Teeth, 
  identified 
  with 
  the 
  median 
  form 
  of 
  the 
  mandible, 
  are 
  char- 
  

   acterized 
  by 
  their 
  thin, 
  oblique, 
  trapezoidal 
  figure, 
  great 
  length 
  of 
  

   the 
  posterior, 
  as 
  compared 
  with 
  that 
  of 
  the 
  anterior, 
  articular 
  bor- 
  

   der, 
  and 
  its 
  strong 
  outward 
  and 
  forward 
  obliquity. 
  The 
  basal 
  rim 
  

   and 
  enamel 
  fold 
  corresponding 
  in 
  cc-adaptation 
  with 
  the 
  opposed 
  bor- 
  

   der 
  of 
  the 
  posterior 
  or 
  terminal 
  tooth, 
  and 
  essentially 
  like 
  the 
  thin- 
  

   ner 
  and 
  very 
  short 
  antero-lateral 
  border 
  ; 
  inner 
  margin 
  very 
  oblique 
  

   from 
  the 
  subacute 
  posterior 
  angle 
  forward 
  to 
  the 
  obtuse 
  anterior 
  

   angle 
  ; 
  coronal 
  surface 
  comparatively 
  plain, 
  or 
  culminating 
  in 
  a 
  low 
  

   ridge 
  near 
  the 
  posterior 
  side. 
  

  

  The 
  maxillary 
  posterior 
  teeth 
  are 
  characterized 
  by 
  their 
  elongate, 
  

   wedge-shaped 
  outline, 
  narrow 
  inner 
  margin, 
  and 
  the 
  narrow 
  posterior 
  

   alation. 
  The 
  postero-lateral 
  or 
  oblique 
  border 
  shows 
  the 
  basal 
  por- 
  

   tion 
  inbeveled, 
  channeled, 
  and 
  defined 
  above 
  by 
  a 
  distinct, 
  inbeveled 
  

   enamel 
  fold; 
  the 
  opposite 
  articular 
  border 
  is 
  relatively 
  short 
  and 
  • 
  

   mostly 
  enveloped 
  in 
  the 
  enamel 
  fold, 
  beneath 
  which 
  projects 
  the 
  

   narrow 
  basal 
  rim 
  ; 
  the 
  inner 
  margin, 
  as 
  in 
  the 
  corresponding 
  form 
  

   of 
  Deltodus, 
  is 
  very 
  oblique 
  in 
  its 
  course 
  from 
  the 
  very 
  obtuse 
  angle 
  

   of 
  the 
  articular 
  border 
  backward 
  to 
  the 
  base 
  of 
  the 
  coronal 
  ridge, 
  

   where 
  it 
  is 
  abruptly 
  deflected 
  at 
  right 
  angles, 
  thence 
  to 
  the 
  posterior 
  

   extremity. 
  The 
  crown 
  presents 
  a 
  simple 
  prominence 
  or 
  ridge 
  along 
  

   the 
  anterior 
  side, 
  with 
  abrupt 
  slope 
  to 
  the 
  articular 
  border, 
  and 
  

   behind, 
  descending 
  into 
  a 
  shallow 
  depression, 
  from 
  which 
  rises 
  the 
  

   narrow 
  wing 
  expansion. 
  

  

  The 
  superficial 
  punctation 
  is 
  very 
  like 
  that 
  observed 
  in 
  Deltodus, 
  

   with 
  similar 
  specific 
  modifications. 
  

  

  There 
  exists 
  so 
  intimate 
  relationship 
  between 
  the 
  forms 
  here 
  

   alluded 
  to 
  and 
  typical 
  Deltodus 
  that 
  we 
  have 
  hesitated 
  in 
  recog- 
  

   nizing 
  for 
  them 
  more 
  than 
  a 
  subgeneric 
  distinctness. 
  But 
  taking 
  

   into 
  consideration 
  the 
  community 
  of 
  characteristics 
  by 
  which 
  they 
  

   are 
  distinguished, 
  and 
  which 
  equally 
  serve 
  to 
  distinguish 
  them 
  from 
  

   Deltodus, 
  this 
  discrimination 
  seems 
  to 
  be 
  founded 
  in 
  tangible 
  super- 
  

   ficial 
  characters 
  that 
  fail 
  not 
  to 
  impress 
  the 
  observer 
  with 
  their 
  im- 
  

   portance^ 
  The 
  greater 
  -the 
  -familiarity 
  with 
  the 
  various 
  examples 
  

   embraced 
  under 
  this 
  group, 
  the 
  differentiation, 
  or 
  tendency 
  thereto, 
  4/^iU 
  

  

  of 
  the 
  median 
  ridge 
  of 
  the 
  anterior 
  coronal 
  prominence 
  further 
  

   widely 
  departs 
  from 
  typical 
  Deltodus, 
  while 
  at 
  the 
  same 
  time 
  it 
  

  

  vitii 
  Pu~ 
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