﻿578 
  

  

  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  

  

  Measurements 
  of 
  the 
  teeth. 
  

  

  Upper. 
  

  

  VS" 
  ^•^«^«-' 
  

  

  E. 
  niobra- 
  

   renaia. 
  

  

  Length 
  molar-premolar 
  scries 
  

  

  Length 
  premolar 
  series 
  

  

  Length 
  molar 
  series 
  

  

  Height 
  of 
  crown 
  of 
  m^ 
  

  

  Pm. 
  2, 
  length 
  

  

  width 
  

  

  protocone 
  

  

  Pm.^, 
  length 
  

  

  width 
  

  

  protocone 
  

  

  Pm.*, 
  length 
  

  

  width 
  

  

  protocone 
  

  

  M> 
  length 
  

  

  width 
  

  

  protocone 
  

  

  MA, 
  length 
  

  

  width 
  

  

  protocone 
  

  

  It.*, 
  length 
  

  

  width 
  

  

  protocone 
  

  

  /.', 
  diameter, 
  side 
  to 
  side.. 
  

  

  diameter, 
  fore 
  and 
  aft. 
  . 
  

   7.2, 
  diameter, 
  side 
  to 
  side 
  . 
  . 
  

  

  diameter, 
  fore 
  and 
  aft. 
  . 
  

   /.«, 
  diameter, 
  side 
  to 
  side. 
  . 
  . 
  

  

  diameter, 
  fore 
  and 
  aft. 
  . 
  

  

  16 
  

  

  31 
  

  

  25 
  

  

  16.5 
  

  

  16 
  

  

  11.5 
  

  

  18 
  

  

  11 
  

  

  20 
  

  

  11 
  

  

  mm. 
  

   180 
  

   94 
  

  

  84 
  

  

  27.5 
  

   14 
  

  

  27 
  

   13.5 
  

  

  30 
  

   17.5 
  

  

  Having 
  compared 
  many 
  of 
  the 
  measurements 
  of 
  the 
  skulls, 
  as 
  

   given 
  above, 
  with 
  the 
  length, 
  it 
  is 
  found 
  that 
  the 
  ratios 
  in 
  the 
  two 
  

   species 
  are 
  not 
  greatly 
  different. 
  Nevertheless, 
  as 
  will 
  be 
  seen 
  from 
  

   the 
  table 
  on 
  page 
  590, 
  tha 
  skull 
  is 
  wider 
  in 
  the 
  present 
  species 
  than 
  in 
  

   the 
  domestic 
  horse 
  and 
  the 
  nose 
  is 
  rather 
  short. 
  The 
  size 
  of 
  the 
  

   brain 
  case 
  is 
  remarkable. 
  Its 
  width, 
  measured 
  above 
  the 
  hinder 
  

   root 
  of 
  the 
  zygomatic 
  arch, 
  is 
  122 
  mm. 
  In 
  the 
  skull 
  of 
  the 
  domestic 
  

   horse, 
  No. 
  843, 
  the 
  width 
  is 
  115 
  mm. 
  It 
  will 
  be 
  seen 
  that 
  the 
  teeth 
  

   agree 
  closely 
  in 
  their 
  dimensions 
  with 
  those 
  of 
  E. 
  caballus, 
  although 
  

   those 
  of 
  the 
  fossil 
  species 
  are 
  somewhat 
  wider, 
  above 
  and 
  below. 
  

   It 
  appears 
  therefore 
  necessary 
  to 
  find 
  most 
  of 
  the 
  specific 
  differences 
  

   in 
  the 
  structure 
  of 
  the 
  teeth. 
  In 
  general 
  the 
  arrangement 
  of 
  the 
  

   enamel 
  of 
  the 
  cheek 
  teeth 
  is 
  simpler 
  than 
  in 
  the 
  domestic 
  horse, 
  as 
  

   seen 
  on 
  the 
  hinder 
  border 
  of 
  the 
  anterior 
  and 
  the 
  front 
  border 
  of 
  the 
  

   posterior 
  lakes 
  (fig. 
  19). 
  Here 
  the 
  enamel 
  band 
  has 
  merely 
  one 
  or 
  

   two 
  short 
  loops, 
  whereas 
  iu 
  the 
  domestic 
  horse 
  it 
  is 
  almost 
  always 
  

   considerably 
  crinkled. 
  The 
  valley 
  which 
  enters 
  the 
  face 
  of 
  the 
  tooth 
  

   from 
  the 
  lingual 
  side, 
  the 
  post-protoconal 
  valley, 
  appears 
  usually 
  to 
  

   extend 
  farther 
  outward 
  than 
  in 
  the 
  domestic 
  horse. 
  In 
  the 
  latter 
  

   the 
  distance 
  from 
  the 
  inner 
  wall 
  of 
  the 
  protocone 
  to 
  the 
  anterior 
  and 
  

   outer 
  extremity 
  of 
  the 
  post-protoconal 
  valley 
  is 
  equal 
  to 
  or 
  less 
  than 
  

   the 
  distance 
  from 
  the 
  latter 
  point 
  to 
  the 
  enamel 
  wall 
  of 
  the 
  median 
  

   ridge, 
  or 
  style, 
  on 
  the 
  outer 
  face 
  of 
  the 
  tooth. 
  In 
  E. 
  niohrarensis 
  

  

  