﻿NEW 
  BRITISH 
  VOLE 
  FROM 
  ORKNEY 
  ISLANDS. 
  245 
  

  

  Measurements 
  in 
  Millimetres 
  of 
  Eight 
  Specimens 
  presented 
  to 
  the 
  

   British 
  Museum, 
  

  

  Sex 
  

  

  Head 
  and 
  

   Body 
  

  

  I.Male 
  

  

  2. 
  Female 
  

  

  3. 
  Male 
  

  

  4. 
  Female 
  

  

  5. 
  Male 
  (type)* 
  

  

  6. 
  Male 
  

  

  7. 
  Immaturemale 
  

   3i 
  months 
  ... 
  

  

  8. 
  Immature 
  fe- 
  

   male, 
  3^- 
  mth. 
  

  

  110 
  

   185 
  

   ISO 
  

   130 
  

   120 
  

   110 
  

  

  105 
  

  

  90 
  

  

  25 
  

   25 
  

   30 
  

   26 
  

   25 
  

   24 
  

  

  23 
  

  

  20 
  

  

  Hind 
  foot 
  

  

  Ear 
  

  

  Length 
  of 
  

  

  Skull 
  * 
  

  

  20 
  

  

  12 
  

  

  broken 
  

  

  16 
  

  

  12 
  

  

  broken 
  

  

  17 
  

  

  11 
  

  

  broken 
  

  

  16 
  

  

  11 
  

  

  broken 
  

  

  20 
  

  

  11 
  

  

  27 
  

  

  16 
  

  

  11 
  

  

  26 
  

  

  17 
  

  

  10 
  

  

  25 
  

  

  18 
  

  

  9 
  

  

  26 
  

  

  Breadth 
  of 
  

   Skull 
  at 
  

   Zygomata 
  

  

  17 
  

   15 
  

  

  18 
  

   17 
  

   17 
  

  

  17 
  

  

  15 
  

  

  On 
  comparing 
  the 
  Orkney 
  Vole 
  with 
  the 
  common 
  British 
  

   species 
  of 
  Field-Vole, 
  the 
  most 
  superficial 
  observer 
  will 
  at 
  once 
  

   be 
  struck 
  by 
  the 
  superior 
  size, 
  the 
  broad, 
  blunt, 
  and 
  heavily 
  

   furred 
  head, 
  and 
  the 
  difference 
  in 
  colour 
  of 
  the 
  northern 
  

   species. 
  The 
  incisor 
  teeth 
  also 
  present 
  a 
  great 
  difference 
  in 
  

   point 
  of 
  size 
  ; 
  the 
  molars, 
  too, 
  are 
  of 
  different 
  pattern. 
  A 
  com- 
  

   parison, 
  too, 
  of 
  the 
  average 
  measurements 
  at 
  once 
  disposes 
  of 
  

   any 
  close 
  association. 
  The 
  following 
  are 
  the 
  measurements 
  in 
  

   millimetres 
  of 
  a 
  typical 
  adult 
  male 
  British 
  Field-Vole, 
  taken 
  in 
  

   Sussex, 
  December, 
  1903 
  : 
  — 
  

  

  Sex 
  ' 
  Head 
  and 
  Body 
  

  

  Tail 
  ' 
  Hind 
  foot 
  

  

  E 
  ai- 
  

  

  Length 
  of 
  

   Skull 
  

  

  Breadth 
  oj 
  

  

  Skull 
  at, 
  

  

  Zygomata 
  

  

  Male 
  1 
  100 
  mm. 
  

  

  24 
  

  

  16 
  

  

  10 
  

  

  25 
  

  

  16 
  

  

  The 
  sexes 
  diner 
  little 
  in 
  size. 
  

  

  It 
  will 
  be 
  noticed 
  therefore 
  that 
  while 
  the 
  average 
  adult 
  male 
  

   Orcadian 
  Vole 
  is 
  much 
  larger 
  than 
  the 
  Field-Vole 
  of 
  the 
  main- 
  

   land, 
  there 
  is 
  still 
  greater 
  disproportion 
  between 
  maximum 
  

   measurements. 
  The 
  only 
  part 
  of 
  the 
  animal 
  which 
  does 
  not 
  

   show 
  this 
  difference 
  is 
  the 
  tail. 
  

  

  Without 
  offering 
  any 
  opinion 
  as 
  to 
  how 
  this 
  large 
  Arctic 
  Vole 
  

  

  * 
  British 
  Museum, 
  No. 
  4. 
  6. 
  21. 
  1. 
  

  

  