﻿422 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  io3 
  

  

  with 
  teeth 
  badly 
  worn; 
  USNM 
  18949, 
  right 
  mandible 
  with 
  P2-M3; 
  

   CM 
  9171, 
  right 
  mandible 
  with 
  P3-M2; 
  CM 
  9365, 
  right 
  mandible 
  with 
  

   P2-M2; 
  CM 
  9363, 
  right 
  mandible 
  with 
  dP2-4; 
  CM 
  9364, 
  right 
  mandible 
  

   with 
  dP2-4. 
  Specimens 
  are 
  from 
  locality 
  Nos. 
  24LC16 
  and 
  24BW18. 
  

  

  Discussion. 
  — 
  In 
  size 
  and 
  tooth 
  characters 
  the 
  material 
  agrees 
  better 
  

   with 
  this 
  species 
  than 
  any 
  of 
  the 
  many 
  which 
  have 
  been 
  described 
  

   from 
  the 
  Lower 
  Oligocene. 
  Also, 
  the 
  small 
  crochet, 
  which 
  character- 
  

   izes 
  M. 
  portentus 
  Douglass, 
  is 
  lacking. 
  

  

  Since 
  this 
  material 
  is 
  more 
  complete 
  than 
  any 
  previously 
  recorded 
  

   from 
  this 
  area, 
  it 
  will 
  be 
  described 
  briefly. 
  

  

  Description. 
  — 
  Upper 
  dentition: 
  P* 
  with 
  protocone 
  well 
  developed, 
  

   protoloph 
  weak, 
  protoconule 
  indistinct, 
  metaloph 
  well 
  developed 
  with 
  

   distinct 
  metaconule, 
  hypostyle 
  distinct, 
  mesostyle 
  weak 
  but 
  distinct, 
  

   paras 
  tyle 
  distinct, 
  no 
  metastyle; 
  P', 
  P*, 
  and 
  M^ 
  quadrangular, 
  pro- 
  

   toconule 
  and 
  metaconule 
  distinct, 
  parastyle 
  and 
  hypostyle 
  distinct, 
  

   metastyle 
  weak, 
  internal 
  cingulum 
  between 
  protocone 
  and 
  hypocone, 
  

   mesostyle 
  strong; 
  M^ 
  similar 
  to 
  M^ 
  except 
  metaconule 
  very 
  indistinct; 
  

   M' 
  similar 
  to 
  M^ 
  except 
  much 
  narrower 
  posteriorly. 
  Measurements 
  

   (in 
  millimeters): 
  

  

  Lower 
  dentition: 
  Pj 
  sub 
  triangular 
  in 
  outline, 
  protoconid 
  reduced, 
  

   metaconid 
  not 
  twinned, 
  entostylid 
  small 
  but 
  distinct, 
  strong 
  external 
  

   cingulum; 
  P3, 
  P4, 
  Mi, 
  and 
  M2 
  essentially 
  similar, 
  strong 
  external, 
  

   anterior, 
  and 
  posterior 
  cinguli, 
  small 
  median 
  external 
  cusp, 
  metaconid 
  

   and 
  entoconid 
  distinctly 
  twinned, 
  parastyHd 
  indistinct; 
  M3 
  with 
  meta- 
  

   conid 
  indistinctly 
  twinned 
  and 
  entoconid 
  not 
  twinned. 
  Measurements 
  

   (in 
  millimeters): 
  

  

  P2-M2 
  

   P3-M2 
  

  

  P2- 
  

  

  P3- 
  

   P4- 
  

  

  Mi. 
  

   M,. 
  

  

  