﻿VERTEBRATES. 
  133 
  

  

  versed 
  by 
  a 
  slight 
  angulation, 
  whence 
  the 
  surface 
  rises 
  with 
  slight 
  

   concavity 
  .into 
  the 
  moderately 
  upraised 
  alation, 
  along 
  the 
  border 
  of 
  

   which 
  the 
  thickened 
  enamel 
  is 
  rounded 
  over 
  in 
  a 
  relatively 
  wide 
  in- 
  

   beveled 
  fold 
  to 
  the 
  basal 
  portion. 
  The 
  inner 
  edge 
  of 
  the 
  crown, 
  in 
  

   some 
  specimens, 
  shows 
  a 
  widish 
  belt 
  of 
  the 
  dense 
  enamel 
  without 
  

   blemish, 
  as 
  it 
  was 
  when 
  enveloped 
  in 
  the 
  formative 
  membrane 
  ; 
  

   where 
  the 
  surface 
  is 
  exfoliated 
  and 
  abraded 
  the 
  coarse 
  punctate 
  

   structure 
  is 
  revealed. 
  The 
  surface 
  is 
  ordinarily 
  marked 
  by 
  fine 
  

   closely 
  arranged 
  punctse, 
  sometimes 
  showing 
  a 
  disposition 
  toward 
  

   transverse 
  arrangement, 
  but 
  otherwise 
  smooth 
  and 
  destitute 
  of 
  cor- 
  

   rugations. 
  Greatest 
  transverse 
  diameter 
  of 
  a 
  mature 
  tooth 
  across 
  

   inner 
  margin 
  16 
  mm. 
  ; 
  length 
  along 
  crest 
  of 
  the 
  anterior 
  lobe 
  to 
  the 
  

   outer 
  inrolled 
  margin 
  7 
  mm. 
  ; 
  or 
  about 
  as 
  great 
  again 
  as 
  the 
  length 
  

   of 
  the 
  extreme 
  antero-lateral 
  border. 
  

  

  Maxillary 
  posterior 
  teeth 
  subelliptical 
  in 
  outline, 
  strongly 
  inrolled 
  

   along 
  the 
  outer 
  margin. 
  Antero-lateral 
  border 
  with 
  a 
  slightly 
  

   oblique 
  forward 
  course, 
  basal 
  portion 
  channeled 
  and 
  defined 
  above 
  

   by 
  a 
  relatively 
  strong, 
  inbeveled 
  coronal 
  fold; 
  postero-lateral 
  border 
  

   converging 
  toward 
  point 
  of 
  inrollment 
  at 
  an 
  angle 
  of 
  30° 
  to 
  40° 
  

   with 
  the 
  opposite 
  side, 
  making 
  a 
  gentle 
  regular 
  curve 
  from 
  the 
  

   produced, 
  acutely-rounded 
  posterior 
  extremity 
  to 
  the 
  inrolled 
  outer 
  

   margin, 
  basal 
  portion 
  rather 
  deeply 
  channeled 
  and 
  expanded 
  beyond 
  

   the 
  coronal 
  border; 
  inner 
  margin 
  broadly 
  arched 
  round 
  the 
  base 
  of 
  

   the 
  posterior 
  prominence, 
  with 
  a 
  broad 
  concavity 
  in 
  the 
  region 
  of 
  

   the 
  median 
  depression, 
  somewhat 
  angularly 
  arched 
  round 
  the 
  ante- 
  

   rior 
  lobe 
  to 
  the 
  obtuse 
  anterior 
  angle. 
  Contour 
  of 
  the 
  coronal 
  

   regions 
  strongly 
  marked, 
  posterior 
  lobe 
  occupying 
  nearly 
  half 
  the 
  

   lateral 
  diameter 
  of 
  the 
  crown, 
  presenting 
  a 
  broad 
  gentle 
  slope 
  pos- 
  

   teriorly, 
  slightly 
  convex 
  above 
  and 
  faintly 
  depressed 
  on 
  nearing 
  the 
  

   border, 
  which 
  is 
  defined 
  by 
  a 
  rather 
  strong 
  inbeveled 
  enamel 
  fold 
  ; 
  

   the 
  anterior 
  declivity 
  abruptly 
  descends 
  from 
  the 
  more 
  or 
  less 
  

   angularly 
  rounded 
  crest 
  with 
  slight 
  concavity, 
  merging 
  into 
  the 
  

   deep, 
  wide 
  median 
  depression; 
  anteiior 
  lobe 
  culminating 
  in 
  a 
  

   sharply 
  rounded 
  crest 
  flanked 
  by 
  nearly 
  equally 
  steep 
  slopes 
  on 
  

   either 
  side, 
  that 
  in 
  front 
  terminating 
  in 
  a 
  narrow 
  revolving 
  groove 
  

   or 
  angulation 
  which 
  is 
  bordered 
  by 
  the 
  narrow, 
  rounded 
  marginal 
  

   fold 
  of 
  the 
  anterior 
  border. 
  Surface 
  appearances 
  the 
  same 
  as 
  noted 
  

   in 
  the 
  mandibular 
  teeth 
  above 
  described, 
  with 
  the 
  same 
  tendency 
  

   to 
  transverse 
  disposition 
  of 
  the 
  punctse 
  in 
  lines 
  more 
  or 
  less 
  coinci- 
  

   dent 
  with 
  the 
  outline 
  of 
  the 
  inner 
  margin 
  of 
  the 
  tooth. 
  A 
  medium 
  

   size 
  individual 
  measures 
  in 
  greatest 
  transverse 
  diameter 
  between 
  

  

  