﻿art, 
  19 
  CONCERNING 
  BIRDS 
  ' 
  TONGUES 
  GARDNER 
  11 
  

  

  In 
  addition 
  a 
  most 
  difficult 
  problem 
  is 
  the 
  explanation 
  of 
  varia- 
  

   tions 
  in 
  closely 
  related 
  birds 
  where 
  presumably 
  the 
  diet 
  is 
  very 
  

   similar. 
  Thus 
  Lucas 
  8 
  called 
  attention 
  to 
  the 
  variation 
  found 
  

   in 
  the 
  genus 
  Melospiza. 
  In 
  M. 
  fasciata 
  a 
  much-frayed 
  tip 
  is 
  

   found, 
  while 
  in 
  M. 
  lincolmi 
  the 
  tip 
  is 
  only 
  slightly 
  bifid 
  and 
  not 
  

   frayed. 
  To 
  this 
  may 
  be 
  added 
  the 
  genus 
  Zosterops, 
  with 
  a 
  forked 
  

   and 
  smooth 
  tongue 
  in 
  Z. 
  lateralis, 
  while 
  it 
  is 
  much 
  curled 
  and 
  

   frayed 
  in 
  Z. 
  simplex 
  and 
  Z. 
  japonica. 
  Still 
  again 
  among 
  the 
  

   warblers 
  of 
  the 
  genus 
  Dendroica 
  it 
  varies 
  from 
  a 
  flat 
  and 
  only 
  

   slightly 
  split 
  organ 
  in 
  D. 
  petechia 
  (fig. 
  155) 
  and 
  D. 
  fusca 
  (fig. 
  158) 
  

   to 
  a 
  much 
  curled 
  split 
  and 
  frayed 
  one 
  in 
  D. 
  tigrina 
  (fig. 
  2). 
  

  

  The 
  taxonomic 
  value 
  of 
  the 
  tongue 
  in 
  birds 
  is 
  an 
  interesting 
  

   question 
  which 
  can 
  only 
  be 
  answered 
  by 
  a 
  systematic 
  survey. 
  It 
  is 
  

   evident 
  that 
  the 
  most 
  useful 
  characters 
  for 
  classification 
  are 
  those 
  

   founded 
  on 
  strict 
  morphological 
  bases 
  and 
  any 
  structure 
  highly 
  

   modified 
  in 
  response 
  to 
  external 
  stimuli 
  is 
  of 
  the 
  least 
  value. 
  But 
  

   no 
  one 
  organ 
  has 
  ever 
  been 
  found 
  that 
  can 
  serve 
  as 
  a 
  complete 
  

   basis 
  for 
  classification. 
  The 
  history 
  of 
  ornithology 
  evidences 
  many 
  

   mistakes 
  due 
  to 
  the 
  use 
  of 
  one 
  character 
  alone, 
  as 
  witness 
  the 
  old 
  

   group 
  Pinnatipedes, 
  including 
  phalaropes, 
  coots, 
  and 
  grebes, 
  through 
  

   similarity 
  of 
  foot 
  structure. 
  In 
  considering 
  the 
  value 
  of 
  the 
  tongue 
  

   it 
  must 
  be 
  recognized 
  that 
  it 
  is 
  a 
  highly 
  adapted 
  organ, 
  but 
  this 
  

   should 
  not 
  rule 
  it 
  out 
  from 
  all 
  taxonomic 
  consideration. 
  If 
  every 
  

   structure 
  adaptively 
  modified 
  be 
  omitted 
  no 
  part 
  of 
  a 
  bird 
  can 
  be 
  

   used, 
  since 
  to 
  a 
  greater 
  or 
  less 
  extent 
  this 
  includes 
  the 
  whole 
  

   organism. 
  Lucas, 
  s 
  taking 
  note 
  of 
  the 
  adaptive 
  modifications, 
  gives 
  

   it 
  very 
  little 
  taxonomic 
  value. 
  There 
  is, 
  however, 
  need 
  of 
  a 
  sys- 
  

   tematic 
  study 
  of 
  this 
  organ 
  in 
  every 
  group, 
  with 
  an 
  evaluation 
  of 
  it 
  

   in 
  each 
  one. 
  While 
  tongues 
  are 
  adaptively 
  modified 
  it 
  may 
  well 
  be 
  

   that 
  these 
  changes 
  are 
  constructed 
  on 
  a 
  type 
  pattern 
  distinctive 
  of 
  

   the 
  group 
  to 
  which 
  the 
  bird 
  belongs 
  and 
  thus 
  indications 
  of 
  affinity 
  

   be 
  given. 
  

  

  Order 
  COLYMBIFORMES 
  

  

  Loons 
  are 
  distinguished 
  from 
  grebes 
  by 
  the 
  fact 
  that 
  the 
  tongues 
  

   of 
  the 
  former 
  have 
  a 
  large 
  patch 
  of 
  spinose 
  processes 
  at 
  the 
  base, 
  

   while 
  the 
  grebes 
  have 
  but 
  a 
  single 
  row 
  posteriorly. 
  Gavia 
  immer 
  

   (fig. 
  23) 
  has 
  a 
  relatively 
  large 
  patch, 
  while 
  this 
  is 
  not 
  so 
  prominent 
  

   in 
  the 
  Pacific 
  loon, 
  Gavia 
  pacifica 
  (fig. 
  22). 
  Podilymbus 
  podiceps 
  

   and 
  sE 
  chmophorm 
  oecidentalis 
  among 
  the 
  grebes 
  have 
  but 
  a 
  weak 
  

   row 
  of 
  spines, 
  which 
  in 
  the 
  eared 
  grebe 
  Colymbus 
  nigricollis 
  cali- 
  

   fomicus 
  (fig. 
  24) 
  are 
  prominent 
  but 
  broad 
  and 
  flat. 
  

  

  8 
  Lucas, 
  F. 
  A. 
  The 
  Taxonomic 
  Value 
  of 
  the 
  Tongue 
  in 
  Birds. 
  The 
  Auk, 
  vol. 
  13, 
  No. 
  2, 
  

   April, 
  1S96, 
  pp. 
  109-115. 
  

  

  