﻿192 
  

  

  Mr. 
  M. 
  A. 
  C. 
  Hiiiton 
  on 
  

  

  From 
  this 
  desciiptiou 
  it 
  is 
  clear 
  that 
  the 
  fossil 
  navicular 
  

   belonged 
  to 
  an 
  animal 
  possessing 
  close 
  affinities 
  with 
  the 
  

   braver 
  I 
  nevertheless, 
  the 
  differences 
  observed 
  are 
  of 
  generic 
  

   importance. 
  A 
  comparison 
  of 
  the 
  articulations 
  shows 
  that 
  

   the 
  fossil 
  formed 
  ])art 
  of 
  a 
  considerably 
  larger 
  foot 
  than 
  that 
  

   of 
  Castor. 
  The 
  only 
  larger 
  beaver-like 
  rodent 
  known 
  from 
  

   the 
  Forest 
  Bed 
  is 
  the 
  Trogontherium, 
  and, 
  in 
  view 
  of 
  all 
  the 
  

   facts, 
  no 
  reasonable 
  doubt 
  can 
  remain 
  that 
  the 
  fossil 
  is 
  rightly 
  

   referred 
  to 
  this 
  genus. 
  In 
  the 
  beaver 
  the 
  fourth 
  metatarsal 
  

   is 
  the 
  longest 
  and 
  stoutest, 
  the 
  third 
  is 
  little 
  shorter 
  though 
  

   more 
  slender, 
  the 
  second 
  and 
  fifth 
  are 
  much 
  smaller, 
  and 
  tiiat 
  

   of 
  the 
  hallux 
  is 
  still 
  further 
  reduced. 
  From 
  the 
  fact 
  that 
  the 
  

   facette 
  for 
  cuneiform 
  III. 
  is 
  narrower, 
  while 
  those 
  for 
  

   cuneiforms 
  II. 
  and 
  I. 
  are 
  wider 
  and 
  more 
  extensively 
  developed 
  

   in 
  tlie 
  fossil, 
  we 
  may 
  infer 
  that 
  tiie 
  disparity 
  in 
  the 
  size 
  of 
  

   the 
  three 
  cuneiforms, 
  and 
  consequently 
  of 
  the 
  first, 
  second, 
  

   ani 
  third 
  metatarsals 
  which 
  they 
  support, 
  was 
  less 
  marked 
  

   iu 
  the 
  Trogontherium 
  than 
  in 
  the 
  beaver. 
  The 
  slighter 
  

   development 
  of 
  the 
  posterior 
  spur 
  in 
  the 
  fossil 
  betokens 
  less 
  

   powerfully 
  developed 
  flexor 
  muscles. 
  The 
  enlargement 
  of 
  

  

  