﻿592 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol.44. 
  

  

  EQUUS 
  EXCELSUS 
  Leidy. 
  

  

  Equus 
  excelsus 
  was, 
  as 
  already 
  stated, 
  described 
  and 
  figured 
  by 
  

   Dr. 
  Joseph 
  Leidy 
  in 
  1869. 
  The 
  exact 
  locaUty 
  where 
  the 
  specimen 
  

   was 
  found 
  is 
  not 
  known, 
  but 
  it 
  was 
  somewhere 
  along 
  the 
  Loup 
  River, 
  

   approximately 
  at 
  the 
  center 
  of 
  the 
  present 
  State 
  of 
  Nebraska. 
  

  

  The 
  teeth 
  of 
  E. 
  excelsus 
  (type) 
  are 
  but 
  little 
  smaller 
  than 
  those 
  of 
  

   E. 
  niobrarensis. 
  That 
  they 
  may 
  be 
  compared, 
  measurements 
  are 
  

   here 
  given. 
  Gidley's 
  figure 
  of 
  these 
  teeth 
  ^ 
  is 
  accurate, 
  except 
  that 
  

   the 
  engraver 
  has 
  made 
  it 
  4 
  mm. 
  too 
  short. 
  

  

  Measurements 
  of 
  teeth 
  of 
  the 
  type 
  of 
  E. 
  excelsus. 
  

  

  Type. 
  

  

  "112' 
  

   A.M.N. 
  

  

  Length 
  of 
  last 
  premolar 
  and 
  3 
  molars. 
  

  

  Length 
  of 
  3 
  molars 
  , 
  

  

  Pm.^, 
  height 
  

  

  length 
  

  

  width 
  

  

  protocone 
  

  

  M}, 
  height 
  

  

  length 
  

  

  widtn 
  

  

  protocone 
  

  

  M?, 
  height 
  

  

  length 
  

  

  width 
  

  

  Erotocone 
  

   eight 
  

  

  length 
  

  

  width 
  

  

  protocone 
  

  

  mm. 
  

   107 
  

   78 
  

   78 
  

  

  16 
  

  

  26 
  

  

  28 
  

  

  14.2 
  

  

  77 
  

  

  26 
  

  

  26 
  

  

  15.5 
  

  

  79 
  

  

  28 
  

  

  22 
  

  

  14 
  

  

  113 
  

   84 
  

   65 
  

   29 
  

   27.5 
  

   12.5 
  

   58 
  

   27 
  

   26 
  

   13.5 
  

   53 
  

   27 
  

   25 
  

   13 
  

   55 
  

   29 
  

   23 
  

   15 
  

  

  It 
  win 
  be 
  seen 
  that 
  no 
  important 
  differences 
  are 
  to 
  be 
  found 
  

   between 
  the 
  teeth 
  of 
  this 
  species 
  and 
  those 
  of 
  E. 
  niobrarensis 
  as 
  regards 
  

   size. 
  There 
  appear, 
  however, 
  to 
  be 
  differences 
  of 
  specific 
  value 
  in 
  

   their 
  structure. 
  The 
  post-protoconal 
  vaUey 
  of 
  E. 
  niobrarensis 
  is 
  

   broader 
  than 
  that 
  of 
  E. 
  excelsus; 
  it 
  extends 
  nearer 
  the 
  center 
  of 
  the 
  

   tooth, 
  and 
  it 
  is 
  more 
  deeply 
  notched 
  at 
  its 
  anterior 
  end. 
  The 
  front 
  

   border 
  of 
  the 
  anterior 
  lake 
  in 
  E. 
  niobrarensis 
  is 
  deeply 
  notched, 
  but 
  

   not 
  notched 
  in 
  E. 
  excelsus. 
  The 
  form 
  of 
  this 
  lake 
  in 
  the 
  two 
  species 
  

   is 
  very 
  different. 
  The 
  hinder 
  border 
  of 
  the 
  posterior 
  lake 
  in 
  E. 
  

   niobrarensis 
  is 
  deeply 
  notched; 
  in 
  E. 
  excelsus, 
  Httle 
  or 
  not 
  at 
  all. 
  

  

  In 
  E. 
  niobrarensis 
  the 
  post-palatine 
  foramen 
  is 
  placed 
  opposite 
  the 
  

   front 
  half 
  of 
  the 
  last 
  molar; 
  in 
  the 
  type 
  of 
  E. 
  excelsus, 
  it 
  is 
  opposite 
  

   the 
  front 
  end 
  of 
  the 
  second 
  molar. 
  

  

  In 
  the 
  American 
  Museum 
  of 
  Natural 
  History 
  is 
  a 
  fragment 
  of 
  a 
  

   right 
  upper 
  jaw 
  which 
  furnishes 
  the 
  same 
  teeth 
  as 
  the 
  type 
  does, 
  the 
  

   last 
  premolar 
  and 
  the 
  three 
  molars 
  (fig. 
  28). 
  It 
  bears 
  the 
  field 
  num- 
  

   ber 
  112 
  and 
  is 
  part 
  of 
  a 
  collection 
  made 
  at 
  Hay 
  Springs, 
  Nebraska, 
  

   in 
  1893, 
  by 
  Wortman, 
  Peterson, 
  and 
  Gidley. 
  For 
  comparison 
  the 
  

   measurements 
  are 
  given 
  in 
  the 
  second 
  column 
  of 
  the 
  preceding 
  table. 
  

  

  :Ball. 
  Amer. 
  Mus. 
  Nat. 
  Hist., 
  vol. 
  14, 
  p. 
  114, 
  fig. 
  9. 
  

  

  