﻿VEETEBEATES. 
  223 
  

  

  amounts 
  to 
  a 
  slight 
  convexity 
  in 
  the 
  long 
  diameter 
  of 
  the 
  tooth, 
  the 
  

   outer 
  border 
  being 
  well 
  defined 
  by 
  a 
  narrow 
  ridge, 
  separated 
  from 
  

   the 
  convex 
  inner 
  area 
  by 
  a 
  shallow, 
  longitudinal 
  depression. 
  The 
  

   anterior 
  margin 
  is 
  gently 
  arched, 
  with 
  a 
  slight 
  concavity 
  near 
  the 
  

   inner 
  angle 
  and 
  rounded 
  into 
  the 
  outer 
  border 
  at 
  the 
  opposite 
  angle, 
  

   the 
  inbeveled 
  basal 
  portion 
  meeting 
  in 
  a 
  sharp 
  angle 
  with 
  the 
  coronal 
  

   surface 
  ; 
  posterior 
  margin 
  describing 
  approximately 
  the 
  same 
  curv- 
  

   ature, 
  the 
  crown 
  defined 
  by 
  a 
  sharp 
  angle, 
  the 
  slightly-inbeveled 
  

   basal 
  portion 
  channeled, 
  the 
  upper 
  portion 
  enveloped 
  in 
  a 
  glassy, 
  

   enamel 
  layer; 
  outer 
  border 
  gently 
  arched, 
  terminating 
  posteriorly 
  

   in 
  a 
  more 
  or 
  less 
  produced 
  spur, 
  the 
  narrow 
  coronal 
  ridge 
  rounded 
  

   to 
  and 
  well 
  defined 
  from 
  the 
  basal 
  rim, 
  which 
  latter 
  is 
  not 
  suf- 
  

   ficiently 
  well-preserved 
  to 
  show 
  its 
  actual 
  outline 
  and 
  magnitude. 
  

   The 
  inner 
  border 
  is 
  nearly 
  straight, 
  with 
  a 
  slightly-oblique 
  course 
  

   forward 
  and 
  outward, 
  and 
  faint 
  angulation 
  near 
  the 
  anterior 
  angle, 
  

   the 
  crown 
  making 
  a 
  sharp 
  angle 
  with 
  the 
  channeled 
  basal 
  wall, 
  and 
  

   margined 
  by 
  a 
  slight-impressed 
  line, 
  forming 
  a 
  narrow 
  border 
  en- 
  

   circling 
  the 
  contiguous 
  sides 
  of 
  the 
  crown. 
  The 
  inferior 
  surface, 
  in 
  

   the 
  perfect 
  state, 
  shows 
  irregular 
  striato-punctation 
  in 
  the 
  slightly- 
  

   concave, 
  longitudinal 
  direction, 
  with 
  a 
  slight 
  elevation 
  about 
  one- 
  

   third 
  the 
  distance 
  from 
  the 
  inner 
  border, 
  where 
  the 
  tooth 
  attains 
  its 
  

   maximum 
  depth. 
  The 
  coronal 
  surface 
  is 
  uniformly 
  minutely 
  punc- 
  

   tate, 
  plainly 
  exhibiting 
  the 
  superficial 
  structural 
  features 
  common 
  to 
  

   the 
  congeneric 
  forms. 
  Transverse 
  diameter 
  across 
  the 
  posterior 
  mar- 
  

   gin, 
  29 
  mm. 
  ; 
  length 
  along 
  inner 
  articular 
  border, 
  17 
  mm. 
  ; 
  greatest 
  

   depth 
  of 
  tooth, 
  6.5 
  mm. 
  

  

  Worn 
  examples 
  of 
  the 
  above 
  described 
  form 
  show 
  a 
  greater 
  trans- 
  

   verse 
  convexity 
  of 
  the 
  coronal 
  surface, 
  while 
  the 
  edges 
  are 
  rounded, 
  

   obliterating 
  the 
  narrow, 
  impressed 
  border 
  mentioned 
  above 
  ; 
  it 
  is 
  not 
  

   improbable 
  also 
  the 
  outer 
  ridge 
  may 
  become 
  nearly 
  obsolete 
  in 
  sim- 
  

   ilarly 
  preserved 
  specimens. 
  The 
  homologous 
  form 
  of 
  the 
  St. 
  Louis 
  

   species 
  Psammodus 
  pie 
  mis 
  presents 
  a 
  striking 
  contrast 
  to 
  the 
  pres- 
  

   ent 
  teeth, 
  being 
  proportionately 
  longer, 
  with 
  less 
  inbeveled 
  posterior 
  

   and 
  anterior 
  walls, 
  and 
  greater 
  lateral 
  convexity 
  of 
  the 
  coronal 
  sur- 
  

   face. 
  Indeed, 
  the 
  nearest 
  allied 
  species 
  at 
  present 
  known 
  is 
  that 
  

   from 
  the 
  Upper 
  Burlington, 
  P. 
  Springeri, 
  the 
  corresponding 
  form 
  of 
  

   which 
  differs 
  in 
  the 
  directly 
  opposite 
  direction 
  of 
  the 
  obliquity 
  of 
  

   the 
  inner 
  articular 
  border, 
  greater 
  length, 
  and 
  more 
  produced 
  pos- 
  

   terior 
  angle 
  of 
  the 
  outer 
  border. 
  

  

  In 
  accordance 
  with 
  the 
  presumed 
  homological 
  relations 
  of 
  the 
  va- 
  

   rious 
  forms 
  of 
  teeth 
  ascribed 
  to 
  the 
  genus, 
  the 
  form 
  pertaining 
  to 
  

  

  