﻿VEETEBEATES. 
  135 
  

  

  Pcecilodus 
  Cestriensis, 
  St. 
  J. 
  and 
  W. 
  

  

  PI. 
  VIII, 
  Fig. 
  15-17. 
  

  

  Teeth 
  of 
  medium 
  or 
  small 
  size, 
  mandibular 
  posterior 
  form 
  having 
  

   the 
  general 
  trapezoidal 
  outline 
  of 
  Cochliodus, 
  or 
  a 
  great 
  transverse 
  

   diameter 
  compared 
  with 
  that 
  in 
  the 
  direction 
  of 
  the 
  strongly 
  arched 
  

   inrollment. 
  Antero-lateral 
  border 
  comparatively 
  short, 
  a 
  distinct 
  

   furrow 
  defining 
  the 
  narrow 
  enamel 
  fold 
  from 
  the 
  shallow 
  basal 
  rim, 
  

   sharply 
  inrolled 
  spirally 
  at 
  the 
  extremity 
  ; 
  inner 
  margin 
  very 
  oblique 
  

   in 
  front, 
  joining 
  the 
  articular 
  border 
  at 
  a 
  very 
  obtuse 
  angle, 
  sud- 
  

   denly 
  rounded 
  at 
  anterior 
  ridge 
  and 
  more 
  broadly 
  so 
  in 
  passing 
  the 
  

   base 
  of 
  the 
  principal 
  ridge, 
  moderately 
  incurved 
  in 
  the 
  intermediate 
  

   space, 
  and 
  again 
  on 
  extending 
  into 
  the 
  somewhat 
  produced 
  posterior 
  

   angle; 
  postero-lateral 
  border 
  moderately 
  arched 
  and 
  rapidly 
  con- 
  

   verging 
  toward 
  point 
  of 
  inrollment, 
  coronal 
  enamel 
  forming 
  a 
  rela- 
  

   tively 
  strong 
  fold 
  defined 
  by 
  a 
  deep 
  narrow 
  sulcus 
  from 
  the 
  inferior 
  

   basal 
  rim, 
  which 
  projects 
  posteriorly 
  beyond 
  the 
  coronal 
  limits, 
  ter- 
  

   minating 
  in 
  a 
  more 
  or 
  less 
  produced 
  spur. 
  Anterior 
  coronal 
  ridge 
  

   nearly 
  as 
  prominent 
  but 
  narrower 
  than 
  that 
  behind, 
  culminating 
  in 
  

   a 
  sharply 
  rounded 
  crest 
  with 
  steep 
  slopes 
  descending 
  to 
  the 
  antero- 
  

   lateral 
  border 
  on 
  the 
  one 
  hand, 
  and 
  into 
  the 
  deep, 
  narrow 
  median 
  

   depression 
  on 
  the 
  other 
  ; 
  principal 
  ridge 
  situate 
  about 
  equidistant 
  

   between 
  the 
  angles 
  of 
  the 
  inner 
  margin, 
  broadly 
  arched 
  transversely 
  

   over 
  the 
  inner 
  third 
  of 
  its 
  extent, 
  but 
  more 
  sharply 
  rounded 
  in 
  the 
  

   outer 
  portion, 
  the 
  posterior 
  slope 
  abrupt, 
  and 
  as 
  in 
  the 
  parallel 
  

   ridge 
  somewhat 
  deeply 
  excavated; 
  posterior 
  depression 
  broad 
  and 
  

   deep, 
  the 
  transversely 
  slightly 
  concave 
  surface 
  steadily 
  rising 
  into 
  

   the 
  wide 
  posterior 
  alation, 
  which 
  comprises 
  about 
  one-third 
  the 
  lat- 
  

   eral 
  diameter 
  of 
  the 
  crown. 
  Surface 
  along 
  the 
  inner 
  margin 
  envel- 
  

   oped 
  in 
  a 
  glassy 
  enamel 
  layer 
  beneath 
  which 
  the 
  minute 
  densely 
  

   crowded 
  puncta3 
  are 
  distinctly 
  visible, 
  and 
  which 
  are 
  laid 
  bare 
  over 
  

   the 
  greater 
  area 
  of 
  the 
  triturating 
  surface 
  in 
  front 
  ; 
  faint 
  transverse 
  

   undulations 
  traverse 
  the 
  crown 
  conforming 
  to 
  the 
  curvature 
  of 
  the 
  

   inner 
  margin, 
  worn 
  specimens 
  exhibiting 
  more 
  distinct 
  irregular 
  

   undulations 
  along 
  the 
  crests 
  of 
  the 
  coronal 
  prominences. 
  A 
  speci- 
  

   men 
  of 
  ordinary 
  size 
  measures 
  across 
  the 
  inner 
  margin 
  16 
  mm.. 
  ; 
  

   length 
  along 
  principal 
  ridge 
  to 
  inrolled 
  outer 
  margin, 
  10 
  mm. 
  ; 
  

   length 
  of 
  anterior 
  articular 
  border, 
  about 
  3.5 
  mm. 
  

  

  Maxillary 
  posterior 
  teeth 
  subelliptical 
  in 
  outline, 
  strongly 
  inrolled 
  

   at 
  the 
  outer 
  margin. 
  Antero-lateral 
  border 
  produced 
  obliquely 
  forward 
  

  

  