﻿296 
  RANID/E. 
  

  

  Brown 
  above, 
  with 
  metallic 
  spots 
  ; 
  caudal 
  crests 
  

   greyish- 
  white, 
  with 
  small 
  brown 
  spots 
  and 
  golden 
  

   dots 
  on 
  the 
  anterior 
  half 
  of 
  the 
  upper 
  crest; 
  some- 
  

   times 
  a 
  series 
  of 
  large 
  brown 
  spots 
  on 
  the 
  upper 
  edge 
  

   of 
  the 
  tail, 
  or 
  a 
  linear 
  series 
  of 
  small 
  golden 
  spots 
  

   along 
  the 
  upper 
  and 
  lower 
  crests 
  ; 
  belly 
  greyish 
  with 
  

   golden 
  clots. 
  

  

  Total 
  length 
  43 
  mm. 
  ; 
  body 
  16; 
  width 
  of 
  body 
  10; 
  

   tail 
  27 
  ; 
  depth 
  of 
  tail 
  9. 
  

  

  Habitat. 
  — 
  Rana 
  arvalis 
  is 
  often 
  described 
  as 
  a 
  

   boreal 
  species, 
  but 
  this 
  is 
  quite 
  incorrect. 
  Its 
  

   northern 
  range 
  extends 
  but 
  slightly 
  beyond 
  that 
  of 
  

   R. 
  esculenta, 
  and 
  stops 
  short 
  by 
  10° 
  of 
  that 
  of 
  R. 
  tern- 
  

   poraria. 
  It 
  is 
  only 
  found 
  on 
  the 
  south-eastern 
  coast 
  

   of 
  Norway, 
  where 
  it 
  is 
  local 
  and 
  rare; 
  in 
  Sweden 
  it 
  

   does 
  not 
  reach 
  much 
  further 
  north 
  than 
  Upsala, 
  

   and 
  in 
  Russia 
  not 
  beyond 
  South-eastern 
  Finland. 
  It 
  

   is 
  really 
  an 
  Eastern 
  species, 
  which, 
  except 
  in 
  the 
  

   south, 
  has 
  much 
  the 
  same 
  range 
  as 
  Bnfo 
  viridis, 
  being 
  

   generally 
  distributed 
  in 
  the 
  eastern 
  parts 
  of 
  Central 
  

   Europe, 
  and 
  becoming 
  more 
  and 
  more 
  local 
  towards 
  

   the 
  Bhine, 
  on 
  the 
  left 
  side 
  of 
  which 
  it 
  is 
  as 
  yet 
  

   only 
  known 
  from 
  a 
  small 
  district 
  in 
  Alsatia 
  and 
  

   Switzerland. 
  The 
  broken, 
  spot-like 
  character 
  of 
  its 
  

   distribution 
  towards 
  the 
  west, 
  and 
  the 
  nature 
  of 
  the 
  

   localities 
  in 
  which 
  it 
  usually 
  occurs, 
  as 
  sphagnum 
  

   bogs, 
  fens, 
  neglected 
  meadows, 
  &c, 
  clearly 
  point 
  to 
  its 
  

   being, 
  in 
  those 
  parts, 
  in 
  process 
  of 
  gradual 
  extinction, 
  

   a 
  relic 
  of 
  a 
  former 
  period, 
  the 
  conditions 
  of 
  which 
  

   are 
  fast 
  disappearing 
  through 
  human 
  agency 
  except 
  

   in 
  the 
  mountains, 
  which 
  this 
  species 
  nowhere 
  ascends 
  

   beyond 
  2000 
  feet. 
  Were 
  R. 
  a 
  walls 
  a 
  boreal 
  form, 
  as 
  

   stated 
  by 
  some 
  authors, 
  its 
  range 
  in 
  Central 
  Europe 
  and 
  

   its 
  absence 
  from 
  the 
  mountains 
  would 
  be 
  not 
  exactly 
  

   unparalleled, 
  but 
  very 
  much 
  more 
  difficult 
  of 
  explana- 
  

   tion. 
  

  

  In 
  Europe 
  the 
  species 
  occurs 
  from 
  the 
  Northern 
  

   and 
  Middle 
  Oural 
  to 
  Holland 
  (near 
  Apeldoorn), 
  several 
  

   localities 
  east 
  of 
  the 
  Bhine 
  (Elberfeld, 
  Siegburg 
  near 
  

  

  