﻿244 
  

  

  THE 
  ZOOLOGIST. 
  

  

  The 
  Orkney 
  Vole, 
  for 
  which 
  I 
  propose 
  the 
  name 
  of 
  Microtus 
  

   orcadensis, 
  sp. 
  nov., 
  may 
  be 
  described 
  as 
  follows 
  : 
  — 
  

  

  General 
  Characters. 
  — 
  Size, 
  in 
  very 
  large 
  males, 
  nearly 
  double 
  

   that 
  of 
  the 
  Common 
  Field-Vole 
  ; 
  skull 
  of 
  adults 
  about 
  26 
  mm., 
  very 
  

   strong, 
  with 
  large 
  incisors; 
  tail, 
  30 
  mm., 
  short 
  and 
  well-haired 
  ; 
  

   zygomata 
  heavy. 
  The 
  long 
  hair 
  on 
  the 
  forehead 
  stands 
  up 
  'promi- 
  

   nently 
  in 
  life. 
  Ears 
  large 
  and 
  well 
  haired. 
  The 
  general 
  appear- 
  

   ance 
  is 
  massive 
  ; 
  the 
  muzzle 
  being 
  particularly 
  blunt, 
  with 
  the 
  strong 
  

   incisors 
  prominent. 
  Skull 
  of 
  the 
  adult 
  male 
  in 
  millimetres: 
  — 
  

   Greatest 
  length 
  above, 
  26 
  ; 
  base 
  length, 
  2J? 
  ; 
  palatal 
  length, 
  15 
  ; 
  

   zygomatic 
  breadth, 
  17 
  ; 
  brain-case, 
  12 
  ; 
  length 
  of 
  molars, 
  6'5 
  ; 
  

   length 
  of 
  nasals, 
  9. 
  And 
  the 
  same 
  may 
  be 
  said 
  of 
  the 
  skulls 
  of 
  

   females. 
  Total 
  length 
  from 
  nose 
  to 
  root 
  of 
  tail, 
  125 
  mm. 
  Hind 
  

   foot, 
  20 
  mm. 
  

  

  Colour. 
  — 
  In 
  full 
  winter 
  pelage 
  the 
  general 
  colour 
  of 
  the 
  upper 
  

   parts 
  is 
  dull 
  sandy 
  brown. 
  This 
  effect 
  is 
  produced 
  by 
  upper 
  and 
  

   minor 
  portion 
  of 
  the 
  hairs 
  being 
  pale 
  yellowish 
  brown, 
  with 
  the 
  long 
  

   protruding 
  hairs 
  black. 
  The 
  major 
  and 
  hidden 
  portion 
  is 
  slaty 
  

   grey. 
  The 
  back 
  hairs 
  are 
  very 
  dense 
  and 
  long, 
  measuring 
  as 
  much 
  

   as 
  15 
  mm. 
  Hair 
  on 
  cheeks 
  and 
  flanks 
  having 
  fewer 
  black 
  hairs, 
  

   more 
  sandy 
  broivn, 
  inclining 
  to 
  russet, 
  whilst 
  the 
  throat 
  is 
  again 
  

   paler, 
  and 
  the 
  whole 
  of 
  the 
  under 
  parts 
  sandy 
  rufous. 
  Hair 
  on 
  the 
  

   legs 
  and 
  feet 
  pale 
  sandy 
  yellow. 
  Demarcation 
  between 
  the 
  upper 
  

   and 
  lower 
  parts 
  is 
  only 
  slightly 
  defined. 
  The 
  ears 
  are 
  heavily 
  

   haired 
  on 
  the 
  inner 
  ridge. 
  This 
  gradually 
  ceases 
  toicards 
  the 
  top, 
  

   whilst 
  the 
  inner 
  surface 
  of 
  the 
  ear 
  itself 
  is 
  thinly 
  covered 
  with 
  small 
  

   sandy 
  hairs. 
  Tail 
  well 
  haired 
  with 
  yellowish 
  hair 
  possessing 
  grey 
  

   under 
  parts. 
  Both 
  in 
  adults 
  and 
  immature 
  s 
  a 
  dark 
  line 
  is 
  some- 
  

   times 
  seen 
  extending 
  from 
  the 
  root 
  to 
  tip 
  of 
  the 
  tail 
  on 
  the 
  upper 
  

   surface. 
  The 
  above 
  describes 
  the 
  full 
  winter 
  pelage. 
  In 
  summer 
  

   the 
  coat 
  of 
  hair 
  is 
  not 
  so 
  dense, 
  and 
  rather 
  more 
  cinnamon-rufous 
  

   all 
  over. 
  The 
  immatures 
  resemble 
  the 
  adults, 
  except 
  that 
  the 
  hair 
  

   on 
  the 
  upper 
  surface 
  of 
  the 
  toes 
  is 
  often 
  white. 
  

  

  

  Dimensions 
  in 
  

  

  Millimetres. 
  

  

  

  

  Adults, 
  female 
  and 
  

  

  male 
  

  

  Head 
  and 
  body 
  Tail 
  

  

  Hind 
  foot 
  

  

  Ear 
  

  

  Ma. 
  c 
  tin 
  ii 
  hi 
  

  

  140 
  

   120 
  

   115 
  

  

  30 
  

   26 
  

  

  22 
  

  

  20 
  

  

  18 
  

   16 
  

  

  12 
  

  

  

  11 
  

  

  

  10 
  

  

  

  

  