﻿E. 
  L. 
  Troxell 
  — 
  An 
  Oliyocene 
  Camel. 
  385 
  

  

  which 
  is 
  so 
  long 
  antero-posteriorly, 
  could 
  be 
  changed 
  into 
  the 
  

   caniniform 
  tooth 
  found 
  in 
  the 
  later 
  genera, 
  viz 
  : 
  Procamelus, 
  

   etc. 
  There 
  is 
  one 
  prominent 
  central 
  and 
  one 
  anterior 
  cusp 
  and 
  

   in 
  general 
  P 
  1 
  resembles 
  somewhat 
  the 
  lower 
  P 
  3 
  which, 
  how- 
  

   ever, 
  is 
  already 
  more 
  nearly 
  caniniform. 
  

  

  This 
  lower 
  tooth, 
  through 
  the 
  prominence 
  of 
  its 
  anterior 
  and 
  

   middle 
  cusps, 
  has 
  a 
  chisel 
  edge 
  with 
  the 
  posterior 
  corner 
  

   beveled 
  off 
  at 
  an 
  angle. 
  It 
  stands 
  higher 
  than 
  the 
  first 
  pre- 
  

   molar 
  of 
  the 
  upper 
  jaw, 
  but 
  is 
  not 
  so 
  long 
  antero-posteriorly 
  

   (height 
  3'3 
  mm 
  , 
  length 
  ant-post. 
  5 
  mm 
  ). 
  Its 
  greatest 
  thickness 
  

   near 
  the 
  roots 
  is 
  nearly 
  3 
  mm 
  and 
  apparently 
  the 
  tooth 
  is 
  set 
  

   with 
  a 
  single 
  heavy 
  root. 
  The 
  diastema 
  before 
  is 
  about 
  3 
  mm 
  , 
  

   that 
  behind, 
  9 
  mm 
  . 
  

  

  The 
  second 
  premolars 
  in 
  the 
  maxillary 
  are 
  of 
  the 
  same 
  long, 
  

   trenchant 
  form 
  in 
  general, 
  though 
  they 
  emphasize 
  the 
  ridges 
  and 
  

   show 
  distinct 
  valleys 
  externally 
  (and 
  internally, 
  to 
  a 
  less 
  extent) 
  

   before 
  and 
  behind 
  the 
  central 
  cone. 
  The 
  cutting 
  edge, 
  slightly 
  

   worn, 
  faces 
  inward 
  and 
  backward. 
  

  

  Upper 
  premolar 
  three, 
  through 
  the 
  elongation 
  of 
  its 
  tetarto- 
  

   cone, 
  has 
  a 
  festoon 
  inclosing 
  a 
  distinct 
  lake 
  in 
  the 
  posterior 
  por- 
  

   tion. 
  Antero-interiorly 
  there 
  is 
  a 
  cusp, 
  the 
  deuterocone 
  of 
  Scott, 
  

   corresponding 
  in 
  position 
  to 
  the 
  protocone 
  of 
  the 
  molars, 
  which 
  

   may 
  in 
  some 
  cases, 
  as 
  for 
  example 
  on 
  the 
  right 
  side, 
  mark 
  the 
  

   outer 
  boundary 
  of 
  a 
  lake 
  or 
  backward 
  trending 
  groove 
  between 
  

   it 
  and 
  its 
  own 
  protocone. 
  A 
  heavy 
  buttress 
  leads 
  from 
  this 
  

   cusp 
  and 
  appears 
  to 
  form 
  a 
  separate, 
  third 
  root. 
  The 
  outer 
  

   wall 
  of 
  the 
  tooth, 
  which 
  is 
  marked 
  by 
  two 
  valleys 
  and 
  three 
  

   ridges, 
  the 
  anterior 
  one 
  of 
  which 
  is 
  a 
  rather 
  prominent 
  style, 
  

   stands 
  high 
  as 
  a 
  cutting 
  edge 
  because 
  the 
  worn 
  surface 
  slopes 
  

   inward 
  at 
  an 
  oblique 
  angle. 
  

  

  P 
  4 
  seems 
  extremely 
  simple 
  and, 
  like 
  that 
  of 
  most 
  ruminants, 
  

   consists 
  of 
  the 
  ordinary 
  two 
  crescents 
  inclosing 
  a 
  shallow 
  lake. 
  

   At 
  the 
  present 
  stage 
  of 
  wear 
  the 
  junction 
  of 
  the 
  protocone 
  and 
  

   deuterocone 
  is 
  not 
  entirely 
  complete. 
  The 
  outer 
  surface 
  of 
  the 
  

   tooth 
  resembles 
  P 
  3 
  and 
  P 
  2 
  and 
  all 
  have 
  rather 
  prominent 
  

   anterior 
  styles. 
  

  

  P 
  2 
  of 
  the 
  lower 
  jaw 
  is, 
  like 
  the 
  ramus 
  at 
  this 
  point, 
  very 
  thin 
  

   transversely, 
  but 
  its 
  antero-posterior 
  diameter, 
  7*5 
  min 
  , 
  is 
  long. 
  

   It 
  is 
  separated 
  by 
  an 
  extensive 
  diastema 
  from 
  the 
  tooth 
  in 
  

   front, 
  but 
  is 
  in 
  conjunction 
  with 
  the 
  premolar 
  behind. 
  

  

  The 
  central 
  cone 
  of 
  P 
  3 
  is 
  very 
  prominent 
  and 
  from 
  its 
  nar- 
  

   now, 
  acute 
  point 
  there 
  extends 
  backward 
  two 
  ridges, 
  one 
  the 
  

   main, 
  trenchant 
  edge 
  joining 
  the 
  single 
  posterior 
  cusp, 
  the 
  

   hypoconid 
  ; 
  the 
  other, 
  the 
  deuteroconid, 
  incloses 
  a 
  very 
  narrow 
  

   lake 
  or 
  valley 
  which 
  opens 
  on 
  the 
  inner 
  side 
  of 
  the 
  tooth. 
  Its 
  

   anterior 
  cusp, 
  the 
  paraconid, 
  is 
  set 
  off 
  conspicuously 
  by 
  the 
  

   short 
  sharp 
  groove 
  behind 
  it. 
  

  

  