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  Variation 
  in 
  Shape 
  of 
  the 
  Eggs 
  of 
  Birds. 
  

  

  is 
  vertical 
  when 
  it 
  perches 
  and 
  horizontal 
  when 
  it 
  flies 
  or 
  

   swims. 
  

  

  How 
  far 
  these 
  hypotheses 
  are 
  consistent 
  with 
  facts 
  it 
  is 
  

   difficult 
  to 
  say, 
  hut 
  the 
  alternative 
  theory 
  that 
  the 
  shape 
  of 
  the 
  

   egg-shell 
  is 
  determined 
  by 
  its 
  internal 
  rather 
  than 
  by 
  its 
  

   external 
  environment 
  is 
  supported 
  by 
  a 
  considerable 
  amount 
  

   of 
  evidence. 
  

  

  The 
  eggs 
  of 
  the 
  Charadriidoi 
  are 
  remarkable 
  for 
  their 
  

   pyriform 
  character, 
  in 
  marked 
  contrast 
  to 
  those 
  of 
  the 
  

   Meropid(B 
  or 
  Alcedinida, 
  which 
  are 
  round, 
  or 
  to 
  those 
  of 
  the 
  

   Columbidce 
  or 
  Caprimulgidcs, 
  which 
  are 
  oval. 
  It 
  can 
  scarcely 
  

   be 
  asserted 
  that 
  the 
  birds 
  composing 
  these 
  five 
  families 
  differ 
  

   much 
  in 
  the 
  positions 
  which 
  they 
  usually 
  assume. 
  The 
  

   CharadriidcB 
  differ 
  from 
  the 
  birds 
  contained 
  in 
  the 
  other 
  four 
  

   families 
  above 
  mentioned 
  in 
  having 
  longer 
  legs. 
  The 
  Hero- 
  

   diones 
  have, 
  however, 
  still 
  longer 
  legs 
  than 
  the 
  Lhnicolm, 
  but 
  

   lay 
  eggs 
  of 
  a 
  much 
  less 
  pyriform 
  shape. 
  It 
  can 
  scarcely 
  be 
  

   asserted 
  that 
  the 
  birds 
  of 
  these 
  two 
  suborders 
  differ 
  mate- 
  

   rially 
  in 
  the 
  positions 
  which 
  they 
  ordinarily 
  assume, 
  but 
  they 
  

   do 
  differ 
  remarkably 
  in 
  the 
  condition 
  of 
  the 
  young 
  at 
  birth. 
  

   The 
  Limicolce 
  are 
  " 
  prsecoces," 
  and 
  are 
  born 
  with 
  long 
  stiff 
  

   legs, 
  so 
  that 
  they 
  can 
  walk 
  at 
  once, 
  whilst 
  the 
  Herodiones 
  are 
  

   " 
  altrices," 
  and 
  are 
  born 
  with 
  comparatively 
  short 
  flexible 
  

   legs, 
  so 
  that 
  they 
  are 
  helpless 
  for 
  many 
  days. 
  

  

  It 
  may 
  perhaps 
  be 
  premature 
  to 
  generalize 
  so 
  far 
  as 
  to 
  say 
  

   that 
  long-legged 
  " 
  prsecoces 
  " 
  {Limicolce, 
  &c.) 
  lay 
  pyriform 
  

   eggs, 
  and 
  short-legged 
  " 
  altrices" 
  [CaprimidgidcB 
  , 
  Alcedinidce 
  , 
  

   Strigidce, 
  Meropidce, 
  &c,) 
  lay 
  round 
  eggs, 
  whilst 
  the 
  birds 
  

   possessing 
  either 
  of 
  the 
  other 
  two 
  possible 
  combinations, 
  

   long-legged 
  " 
  altrices 
  '' 
  [Herodiones, 
  &c.) 
  and 
  short-legged 
  

   " 
  prsecoces 
  " 
  [Anseres, 
  &c,), 
  lay 
  oval 
  eggs. 
  This 
  hypothesis, 
  

   however, 
  appears 
  to 
  be 
  quite 
  as 
  tenable 
  as 
  that 
  propounded 
  

   by 
  Dr, 
  Nicolsky. 
  But 
  the 
  subject 
  is 
  a 
  new 
  one 
  and 
  requires 
  

   patient 
  investigation. 
  It 
  cannot, 
  nevertheless, 
  be 
  doubted 
  

   that 
  there 
  are 
  good 
  reasons 
  for 
  the 
  diversities 
  in 
  the 
  shape 
  

   of 
  birds^ 
  eggs, 
  as 
  well 
  as 
  for 
  their 
  variation 
  in 
  colour, 
  and 
  

   there 
  is 
  probably 
  more 
  than 
  one 
  cause 
  operating 
  in 
  this 
  

   direction. 
  

  

  