﻿580 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol.44. 
  

  

  face 
  is 
  short, 
  not 
  being 
  permitted 
  to 
  push 
  itself 
  in 
  between 
  the 
  adja- 
  

   cent 
  ends 
  of 
  the 
  two 
  longitudinal 
  loops 
  of 
  enamel. 
  In 
  the 
  domestic 
  

   horse 
  the 
  outer 
  valley 
  insinuates 
  itself 
  between 
  the 
  two 
  longitudinal 
  

   loops 
  of 
  the 
  true 
  molars. 
  

  

  The 
  first 
  and 
  second 
  upper 
  incisors 
  have 
  deep 
  cups 
  (text-fig. 
  19; 
  

   pi. 
  69, 
  fig. 
  4) 
  . 
  If 
  there 
  was 
  originally 
  a 
  notch 
  on 
  the 
  hinder, 
  or 
  lingual, 
  

   lip 
  of 
  the 
  cup 
  of 
  the 
  first 
  incisors, 
  all 
  traces 
  of 
  it 
  have 
  been 
  worn 
  away. 
  

   There 
  seems 
  to 
  have 
  been 
  a 
  very 
  shallow 
  notch 
  on 
  the 
  lingual 
  lip 
  of 
  

   the 
  second 
  incisor. 
  The 
  third 
  incisors 
  had 
  just 
  begun 
  to 
  suffer 
  wear. 
  

   Each 
  has 
  a 
  cup 
  about 
  20 
  mm. 
  deep, 
  but 
  the 
  lip 
  on 
  the 
  lingual 
  side 
  is 
  

   notched 
  nearly 
  to 
  the 
  bottom 
  of 
  the 
  cup. 
  The 
  hinder 
  part 
  of 
  this 
  lip 
  

   rounds 
  into 
  the 
  opposite, 
  or 
  buccal, 
  lip, 
  between 
  the 
  middle 
  and 
  

   hinder 
  thirds 
  of 
  the 
  latter. 
  

  

  There 
  was 
  evidently 
  a 
  shallow 
  notch 
  in 
  the 
  lingual 
  lip 
  of 
  the 
  second 
  

   lower 
  incisor 
  (pi. 
  71, 
  fig. 
  1). 
  The 
  cup 
  of 
  the 
  third 
  incisor 
  is 
  very 
  

   incomplete. 
  Its 
  lingual 
  lip 
  is 
  notched 
  broadly 
  and 
  nearly 
  to 
  the 
  bot- 
  

   tom 
  of 
  the 
  cup. 
  This 
  lip 
  is 
  represented 
  by 
  a 
  descending 
  ridge 
  in 
  

   front 
  and 
  by 
  a 
  tubercle 
  about 
  the 
  middle 
  of 
  the 
  lingual 
  face 
  of 
  the 
  

   tooth. 
  The 
  remainder 
  of 
  this 
  face 
  is 
  concave 
  transversely. 
  

  

  In 
  the 
  American 
  Museum 
  of 
  Natural 
  History 
  is 
  a 
  mandibular 
  

   symphysis 
  which 
  the 
  writer 
  regards 
  as 
  belonging 
  to 
  E. 
  niohrarensis. 
  

   It 
  bears 
  the 
  collector's 
  number 
  24. 
  It 
  presents 
  all 
  the 
  permanent 
  

   incisors, 
  of 
  which 
  the 
  first 
  and 
  second 
  are 
  somewhat 
  worn 
  (pi. 
  71, 
  

   fig. 
  2). 
  The 
  third 
  on 
  each 
  side 
  had 
  made 
  its 
  w^ay 
  through 
  the 
  bone, 
  

   but 
  not 
  yet 
  through 
  the 
  gum. 
  Just 
  outside 
  of 
  the 
  front 
  border 
  of 
  

   each 
  is 
  seen 
  the 
  root 
  of 
  the 
  milk 
  incisor 
  just 
  about 
  to 
  be 
  displaced. 
  

   The 
  cup 
  of 
  the 
  third 
  permanent 
  incisor 
  has 
  a 
  low 
  lingual 
  lip, 
  not 
  well 
  

   shown 
  in 
  the 
  figure, 
  but 
  the 
  bottom 
  of 
  the 
  cup 
  extends 
  25 
  mm. 
  

   below 
  it. 
  This 
  tooth 
  is 
  thus 
  quite 
  different 
  from 
  the 
  corresponding 
  

   one 
  of 
  the 
  type. 
  Doubtless 
  here 
  as 
  in 
  other 
  characters 
  there 
  is 
  a 
  

   good 
  deal 
  of 
  variation. 
  Even 
  in 
  the 
  domestic 
  horse 
  there 
  is 
  consider- 
  

   able 
  variation 
  in 
  the 
  completeness 
  of 
  the 
  cup 
  of 
  the 
  third 
  incisor. 
  

   Mr. 
  Gidley 
  ' 
  has 
  referred 
  to 
  this 
  variation 
  and 
  published 
  three 
  figures. 
  

   Nevertheless 
  in 
  the 
  domestic 
  horse 
  the 
  absence 
  of 
  the 
  cup 
  is 
  a 
  rare 
  

   occurrence; 
  and 
  we 
  may 
  expect 
  to 
  find 
  in 
  E. 
  niohrarensis 
  some 
  con- 
  

   dition 
  that 
  prevails. 
  Possibly 
  this 
  tooth 
  in 
  the 
  type 
  is 
  less 
  completely 
  

   developed 
  than 
  usual; 
  or 
  it 
  is 
  possible 
  that 
  the 
  piece 
  of 
  jaw 
  numbered 
  

   24 
  belongs 
  really 
  to 
  some 
  other 
  species. 
  The 
  condition 
  of 
  the 
  incisor 
  

   in 
  the 
  type 
  is 
  not 
  advanced 
  really 
  beyond 
  that 
  of 
  the 
  same 
  tooth 
  in 
  

   a 
  jaw 
  that 
  is 
  referred 
  provisionally 
  to 
  E. 
  excelsus 
  (pi. 
  71, 
  fig 
  3). 
  

   This 
  has 
  the 
  catalogue 
  number 
  2762 
  in 
  the 
  American 
  Museum 
  of 
  

   Natural 
  History. 
  

  

  The 
  following 
  notes 
  and 
  measurements 
  have 
  been 
  taken 
  from 
  No. 
  

   2725 
  of 
  the 
  American 
  Museum 
  of 
  Natural 
  History, 
  New 
  York, 
  the 
  

  

  1 
  Bull. 
  Amer. 
  Mus. 
  Nat. 
  Hist., 
  vol. 
  14, 
  p. 
  103, 
  fig, 
  6, 
  

  

  