﻿408 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  los 
  

  

  Order 
  RODENTIA 
  

   Family 
  Sciuravidae 
  

  

  Prosciurus 
  cf. 
  relictus 
  (Cope) 
  

  

  USNM 
  18857, 
  left 
  mandible 
  with 
  P4-M3; 
  USNM 
  18858, 
  left 
  man- 
  

   dible 
  with 
  P4-M1. 
  Both 
  specimens 
  are 
  from 
  locality 
  No. 
  24LC15. 
  

  

  The 
  enamel 
  patterns 
  of 
  the 
  teeth 
  and 
  the 
  measurements 
  agree 
  

   with 
  the 
  figures 
  and 
  description 
  by 
  A. 
  E. 
  Wood 
  (1937, 
  p. 
  168) 
  but 
  

   this 
  material 
  does 
  not 
  permit 
  any 
  additions 
  to 
  his 
  discussion. 
  Meas- 
  

   urements 
  of 
  teeth 
  (in 
  millimeters) 
  : 
  

  

  USNM 
  18857 
  

  

  Length 
  Width 
  

  

  P4-M3 
  7.2 
  

  

  P4 
  1.5 
  1.6 
  

  

  Ml 
  1.6 
  1.7 
  

  

  M2 
  1.7 
  1.9 
  

  

  M3 
  2.2 
  1.6 
  

  

  Family 
  Ischyromyidae 
  

  

  Ischyromys 
  cf. 
  pliacus 
  Troxell 
  

  

  USNM 
  18908, 
  right 
  mandible 
  with 
  P4-M3; 
  USNM 
  18909, 
  left 
  

   mandible 
  with 
  P4-M2; 
  USNM 
  18920, 
  right 
  mandible 
  with 
  M1-M3. 
  

   Specimens 
  are 
  from 
  locality 
  No. 
  24LC16. 
  

  

  This 
  material 
  does 
  not 
  permit 
  additions 
  to 
  our 
  knowledge 
  of 
  the 
  

   species. 
  

  

  Titanotheriomys 
  veterior 
  Matthew 
  

  

  USNM 
  18904, 
  a 
  palate 
  with 
  dPg-Ms; 
  USNM 
  18905, 
  a 
  palate 
  with 
  

   dPi-Ma; 
  USNM 
  18907, 
  left 
  mandible 
  with 
  P4-M3. 
  Specunens 
  are 
  

   from 
  locality 
  No. 
  24LC16. 
  

  

  This 
  material 
  does 
  not 
  permit 
  any 
  additions 
  to 
  our 
  knowledge 
  of 
  

   this 
  species. 
  

  

  Family 
  Castoridae 
  

  

  Paleocastor 
  cf. 
  gradatus 
  (Cope) 
  

  

  USNM 
  18963, 
  palate 
  Avith 
  left 
  P*-M^ 
  from 
  locality 
  No. 
  24LC18; 
  

   USNM 
  18962, 
  left 
  mandibular 
  fragment 
  with 
  P4-M2, 
  from 
  locality 
  

   No. 
  24LC20. 
  

  

  This 
  material 
  is 
  referred 
  to 
  this 
  species 
  on 
  the 
  basis 
  of 
  size. 
  As 
  

   pointed 
  out 
  by 
  Stirton 
  (1935, 
  p. 
  409), 
  this 
  species 
  is 
  very 
  close 
  to 
  

   P. 
  peninsulatus 
  (Cope). 
  Definite 
  allocation 
  of 
  the 
  Canyon 
  Ferry 
  

   material 
  must 
  await 
  the 
  acquisition 
  of 
  better 
  specimens. 
  

  

  