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XXXVII.  Additional  Remarks  on  the  Genus  Lagotis,  with  some  account  of  a  second  Spe- 
cies referrible  to  it.    By  E.  T.  Bennett,  Esq.,  F.L.S.,  Sec.  Z.S. 
Communicated  May  26,  1835. 
The  brief  notice  which  I  am  about  to  lay  before  the  Society  may  be  regarded  as  sup- 
plemental to  the  communication  '  On  the  Chinchillidce'  made  to  it  in  the  spring  of  1833, 
and  published  in  the  First  Part  of  the  '  Transactions''.  Its  object  is  to  characterize  a 
second  species  of  the  genus  Lagotis,  a  genus  originally  proposed  by  me  in  the  summer  of 
1832,  and  described  in  detail  in  the  paper  referred  to  ;  in  which  were  included  an  account 
of  the  external  form,  the  visceral  anatomy,  and  the  osteology  of  the  genus,  as  observed  in 
the  only  individual  which  I  had  seen  of  the  single  species  then  comprised  in  it.  A  skin 
of  a  second  species  has  since  come  into  the  possession  of  the  Society,  having  been  ac- 
quired by  purchase  from  Mr.  Gould,  who  bought  it  out  of  a  collection  believed  to  have 
been  brought  from  the  Chilian  Andes  :  this  skin  furnishes  the  sole  materials  within  my 
reach  for  the  elucidation  of  the  characters  of  the  animal  in  question. 
Lagotis,  it  will  be  remembered,  differs  externally  from  Chinchilla  by  the  possession  of 
four  toes  on  each  of  its  feet,  instead  of  five  on  the  anterior  and  four  on  the  posterior ; 
and  by  the  greater  length  of  its  tail,  which  is  nearly  equal  to  that  of  the  body  and  head 
taken  together,  while  in  Chinchilla  the  length  of  the  tail,  exclusive  of  the  hairs,  is 
scarcely  more  than  one  half  of  that  of  the  body  and  head.  To  these  characters  I  had 
formerly  added  that  derived  from  the  greater  length  of  the  ears  in  Lagotis  as  compared 
with  those  of  Chinchilla,  these  organs  being  in  Lag.  Cuvieri  equal  in  length  to  the 
distance  interposed  between  their  base  and  the  muzzle  of  the  animal,  while  in  the  latter 
they  scarcely  exceed  three  fourths  of  that  distance  ;  but  as  this  character  does  not  ob- 
tain in  the  animal  before  me,  it  can  no  longer  be  regarded  as  generic.  In  the  second 
species  of  Lagotis  the  ears  have  nearly  the  same  comparative  length  as  in  Chinch,  lani- 
gera  ;  but  they  do  not  possess  the  amplitude  of  lateral  development  which  distinguishes 
those  of  the  latter  animal. 
This  diminished  length  of  the  ears  in  the  second  species  of  Lagotis  affords,  perhaps, 
the  most  readily  appreciable  distinguishing  mark  between  it  and  Lag.  Cuvieri ;  but 
there  are  other  characters  of  distinction  between  them  which  may  be  thus  expressed  : 
•  p.  35. 
