﻿VEETEBEATES. 
  131 
  

  

  Genus 
  PCECILODUS, 
  Agassiz. 
  

   Pcecilodus 
  Vaksoviensis, 
  St. 
  J. 
  and 
  W. 
  

  

  PI. 
  VIII, 
  Fig. 
  13, 
  14. 
  

  

  Posterior 
  teeth 
  of 
  the 
  upper 
  jaw 
  of 
  small 
  size, 
  subelliptical 
  in 
  

   outline, 
  strongly 
  arched 
  in 
  the 
  direction 
  of 
  inrollment. 
  Antero- 
  

   lateral 
  border 
  slightly 
  oblique 
  to 
  the 
  inner 
  margin 
  forward 
  and 
  out- 
  

   ward 
  ; 
  postero 
  — 
  lateral 
  border 
  gently 
  arched 
  and 
  converging 
  toward 
  

   inrolled 
  outer 
  margin 
  at 
  an 
  angle 
  of 
  30°, 
  more 
  or 
  less, 
  with 
  the 
  

   antero-lateral 
  border; 
  inner 
  margin 
  moderately 
  concave 
  in 
  the 
  

   median 
  region, 
  broadly 
  arched 
  round 
  the 
  posterior 
  lobe 
  to 
  the 
  

   acutely 
  rounded 
  extremity, 
  and 
  similarly 
  arched 
  round 
  the 
  base 
  of 
  

   the 
  less 
  prominent 
  anterior 
  lobe 
  to 
  the 
  obtuse 
  anterior 
  angle. 
  Cor- 
  

   onal 
  region 
  presenting 
  a 
  very 
  oblique, 
  moderately 
  elevated, 
  regularly 
  

   transversely 
  arched 
  posterior 
  lobe, 
  a 
  slight 
  sulcus 
  extending 
  along 
  

   the 
  outer 
  side 
  parallel 
  with 
  the 
  postero-lateral 
  border, 
  anteriorly 
  

   defined 
  by 
  the 
  moderately 
  excavated 
  median 
  depression; 
  the 
  muti- 
  

   lated 
  condition 
  of 
  the 
  neck 
  does 
  not 
  permit 
  the 
  contour 
  of 
  the 
  

   anterior 
  lobe 
  to 
  be 
  satisfactorily 
  made 
  out, 
  although 
  it 
  seems 
  to 
  

   have 
  been 
  moderately 
  arched 
  transversely. 
  The 
  posterior 
  lobe 
  shows 
  

   a 
  few 
  relatively 
  strong 
  transverse 
  corrugations, 
  which 
  are 
  obsolete 
  

   in 
  worn 
  examples 
  ; 
  surface 
  punctation 
  fine 
  and 
  moderately 
  spaced* 
  

   Transverse 
  diameter 
  of 
  a 
  mature 
  tooth 
  at 
  the 
  innej* 
  margin 
  12.5 
  mm. 
  ; 
  

   length 
  of 
  antero-lateral 
  border 
  4 
  mm. 
  

  

  The 
  above 
  species 
  is 
  represented, 
  in 
  the 
  collection 
  of 
  Mr. 
  Van 
  

   Home 
  by 
  only 
  two 
  examples 
  of 
  the 
  maxillary 
  terminal 
  form. 
  The 
  

   specimens 
  are 
  mutilated 
  in 
  the 
  anterior 
  region, 
  but 
  the 
  posterior 
  

   prominence 
  exhibits 
  the 
  characteristic 
  contour 
  prevalent 
  in 
  certain 
  

   species 
  of 
  the 
  genus, 
  hence 
  its 
  present 
  reference. 
  The 
  transverse 
  

   undulations 
  of 
  the 
  posterior 
  lobe 
  recall 
  the 
  Chester 
  species, 
  P. 
  Ces- 
  

   triensis, 
  although 
  they 
  are 
  less 
  in 
  number 
  and 
  not 
  so 
  deeply 
  im- 
  

   pressed 
  in 
  the 
  interspaces; 
  while 
  the 
  antero-lateral 
  border 
  seems 
  

   to 
  be 
  longer 
  and 
  less 
  obliquely 
  curved 
  outward 
  and 
  forward. 
  Its 
  

   relations 
  with 
  P. 
  St. 
  Ludovicl 
  are 
  much 
  less 
  intimate, 
  the 
  presence 
  

   of 
  the 
  transverse 
  corrugations 
  of 
  the 
  posterior 
  lobe 
  offering 
  a 
  marked 
  

   distinguishing 
  feature 
  in 
  contrast 
  with 
  that 
  species. 
  Should 
  the 
  

   anterior 
  lobe 
  be 
  found, 
  from 
  the 
  examination 
  of 
  perfect 
  individuals 
  

   to 
  present 
  a 
  regularly 
  convex 
  elevation, 
  instead 
  of 
  an 
  angularly 
  

   arched 
  ridge, 
  such 
  as 
  is 
  characteristic 
  of 
  the 
  genus 
  Poccilodus, 
  the 
  

  

  