﻿VEETEBEATES. 
  115 
  

  

  externa] 
  enamel 
  layer 
  is 
  densest. 
  A 
  mature 
  specimen 
  measures 
  in 
  

   greatest 
  breadth 
  between 
  the 
  inner 
  angles 
  30 
  mm. 
  more 
  or 
  less, 
  

   length 
  along 
  antero-lateral 
  border 
  14 
  mm. 
  

  

  With 
  the 
  exception 
  of 
  the 
  narrow 
  median 
  teeth, 
  the 
  forms 
  whose 
  

   specific 
  identity 
  is 
  here 
  recognized 
  are 
  represented 
  in 
  about 
  equal 
  

   numbers 
  of 
  individual 
  teeth 
  in 
  the 
  collections. 
  The 
  mandibular 
  pos- 
  

   terior 
  form 
  exhibits 
  some 
  variation, 
  especially 
  in 
  certain 
  examples 
  

   which 
  show 
  faint 
  revolving 
  ridges 
  or 
  furrows 
  over 
  the 
  broad 
  anterior 
  

   slope 
  of 
  the 
  coronal 
  prominence, 
  as 
  illustrated 
  in 
  one 
  of 
  the 
  figures 
  

   representing 
  a 
  tooth 
  referred 
  to 
  this 
  species. 
  The 
  latter 
  feature 
  also 
  

   recurs 
  in 
  some 
  of 
  tbe 
  Streblodoid 
  teeth 
  of 
  the 
  upper 
  jaw, 
  as 
  already 
  

   noticed, 
  and 
  although 
  the 
  absence 
  of 
  these 
  obscure 
  furrows 
  and 
  

   ridges 
  does 
  not 
  in 
  all 
  cases 
  appear 
  to 
  be 
  attributable 
  to 
  the 
  acci- 
  

   dents 
  of 
  wear, 
  their 
  presence 
  in 
  certain 
  individuals 
  is 
  not 
  associated 
  

   with 
  other 
  characters 
  which 
  might 
  be 
  deemed 
  sufficient 
  grounds 
  for 
  

   their 
  separation 
  from 
  the 
  specific 
  relations 
  here 
  recognized. 
  Amongst 
  

   the 
  latter 
  there 
  occurs 
  a 
  single 
  individual 
  from 
  Buffington 
  creek, 
  

   which, 
  in 
  the 
  relative 
  proportions 
  of 
  the 
  coronal 
  regions 
  with 
  which 
  

   are 
  associated 
  other 
  features, 
  offer 
  in 
  the 
  main 
  rather 
  marked 
  con- 
  

   trasts 
  with 
  the 
  superficial 
  characteristics 
  noticeable 
  in 
  the 
  typical 
  

   examples 
  of 
  the 
  form 
  described 
  above. 
  These 
  consist 
  in 
  the 
  rela- 
  

   tively 
  wide 
  posterior 
  lobe, 
  the 
  less 
  distinct 
  angular 
  culmination 
  of 
  

   its 
  crest 
  and 
  gentler 
  anterior 
  declivity, 
  proportionately 
  narrower 
  

   median 
  depression, 
  more 
  regularly 
  transversely 
  arched 
  anterior 
  lobe, 
  

   and 
  the 
  upward 
  and 
  forward 
  deflection 
  of 
  the 
  imbrications 
  or 
  trans- 
  

   verse 
  rugae 
  in 
  crossing 
  the 
  median 
  depression, 
  constituting 
  striking 
  

   features 
  in 
  contradistinction 
  of 
  those 
  recognized 
  in 
  consequence 
  of 
  

   their 
  prevalence 
  as 
  normal 
  in 
  'the 
  typical 
  representatives. 
  Illustra- 
  

   tions 
  of 
  the 
  latter 
  specimen 
  are 
  also 
  introduced, 
  although 
  its 
  iden- 
  

   tity 
  with 
  the 
  present 
  species 
  is 
  only 
  provisionally 
  inferred. 
  Also 
  

   amongst 
  the 
  few 
  representatives 
  of 
  the 
  mandibular 
  median 
  form 
  the 
  

   normal 
  condition 
  described 
  above 
  is 
  departed 
  from 
  in 
  appreciable 
  

   degree, 
  presenting 
  a 
  form 
  distinguished 
  by 
  a 
  relatively 
  elevated 
  reg- 
  

   ularly 
  arched 
  coronal 
  prominence 
  and 
  correspondingly 
  depressed 
  

   anterior 
  slope, 
  in 
  which 
  the 
  oblique 
  transverse 
  rugae 
  are 
  more 
  inter- 
  

   rupted 
  in 
  continuity 
  than 
  occurs 
  in 
  the 
  case 
  of 
  the 
  typical 
  individ- 
  

   uals. 
  The 
  somewhat 
  pronounced 
  variations 
  noted 
  may 
  indeed 
  con- 
  

   stitute 
  permanent 
  characteristics 
  such 
  as 
  a 
  larger 
  suite 
  of 
  specimens 
  

   might 
  prove 
  to 
  possess 
  specific 
  value. 
  But 
  at 
  the 
  present 
  time, 
  

   owing 
  chiefly 
  to 
  the 
  imperfect 
  state 
  of 
  preservation 
  of 
  the 
  material 
  

   in 
  which 
  many 
  important 
  details 
  are 
  masked, 
  the 
  evidence 
  is 
  not 
  

  

  