﻿8 
  PROCEEDINGS 
  OP 
  THE 
  NATIONAL 
  MUSEUM 
  vou 
  67 
  

  

  In 
  this 
  group 
  falls 
  also 
  the 
  simple 
  fleshy 
  tongues 
  of 
  the 
  gallina- 
  

   ceous 
  birds 
  (fig. 
  7). 
  

  

  2. 
  Fish 
  eaters, 
  where 
  the 
  tongue 
  is 
  used 
  to 
  hold 
  slippery 
  prey. 
  

   In 
  these 
  it 
  is 
  found 
  to 
  be 
  plentifully 
  supplied 
  with 
  sharp, 
  stiff 
  

   retrorse 
  spines. 
  These 
  may 
  be 
  distributed 
  over 
  the 
  whole 
  sur- 
  

   face, 
  as 
  in 
  the 
  penguins, 
  edging 
  the 
  lateral 
  margin 
  only 
  as 
  in 
  the 
  

   fulmars 
  and 
  shearwaters 
  (fig. 
  8), 
  as 
  a 
  patch 
  of 
  stiff 
  spines 
  situated 
  

   at 
  the 
  base, 
  as 
  in 
  the 
  loons, 
  or 
  a 
  double 
  row 
  on 
  the 
  surface, 
  as 
  in 
  

   mergansers 
  (fig. 
  10). 
  A 
  distinction 
  must 
  be 
  drawn 
  between 
  fish 
  

   eaters 
  that 
  use 
  the 
  tongue 
  and 
  those 
  in 
  which 
  the 
  food 
  is 
  bolted 
  

   whole, 
  where 
  it 
  has 
  lost 
  its 
  function 
  and 
  a 
  different 
  condition 
  pre- 
  

   vails. 
  

  

  3. 
  A 
  diet 
  of 
  a 
  multiplicity 
  of 
  small 
  things 
  strained 
  from 
  the 
  water 
  

   is 
  associated 
  with 
  the 
  complex 
  tongues 
  of 
  the 
  Anatidae 
  (fig. 
  9). 
  

  

  Typically 
  it 
  is 
  roughly 
  rectangular 
  in 
  shape 
  and 
  is 
  thick 
  and 
  fleshy. 
  

   The 
  tip 
  is 
  composed 
  of 
  a 
  cornified 
  rounded 
  flaplike 
  process. 
  Pos- 
  

   terior 
  to 
  this 
  the 
  tongue 
  is 
  broad 
  with 
  a 
  median 
  groove 
  and 
  provided 
  

   laterally 
  with 
  a 
  double 
  row 
  of 
  heavy 
  hairs, 
  the 
  upper 
  overhanging 
  

   the 
  lower 
  like 
  a 
  thatched 
  roof. 
  Toward 
  the 
  posterior 
  half 
  the 
  upper 
  

   row, 
  by 
  a 
  process 
  of 
  agmination 
  of 
  the 
  hairs, 
  becomes 
  converted 
  to 
  a 
  

   series 
  of 
  large, 
  heavy 
  spines, 
  which 
  vary 
  in 
  number 
  with 
  the 
  differ- 
  

   ent 
  species. 
  Coincidentally 
  the 
  edges 
  of 
  the 
  median 
  groove 
  become 
  

   cornified 
  with 
  rough, 
  toothlike 
  processes. 
  Lateral 
  to 
  these 
  the 
  sur- 
  

   face 
  of 
  the 
  tongue 
  is 
  nodular 
  or 
  papillar 
  and 
  plentifully 
  supplied 
  

   with 
  openings 
  of 
  ducts 
  of 
  muscous 
  glands. 
  The 
  posterior 
  portion 
  of 
  

   the 
  tongue 
  is 
  made 
  up 
  of 
  a 
  fleshy 
  eminence 
  heavily 
  armed 
  with 
  

   strong 
  spines. 
  

  

  The 
  method 
  of 
  use 
  is 
  interesting. 
  The 
  tongue 
  is 
  depressed, 
  allow- 
  

   ing 
  water 
  to 
  run 
  along 
  the 
  groove, 
  it 
  is 
  then 
  raised 
  against 
  the 
  palate, 
  

   the 
  water 
  squirted 
  out 
  from 
  the 
  sides 
  through 
  the 
  hairy 
  edges, 
  

   straining 
  out 
  and 
  leaving 
  the 
  solids. 
  

  

  Considerable 
  variation 
  is 
  seen, 
  depending 
  on 
  the 
  use 
  of 
  this 
  organ 
  

   and 
  the 
  width 
  of 
  the 
  bill. 
  Thus 
  in 
  the 
  geese 
  and 
  swans 
  where 
  it 
  is 
  

   used 
  for 
  tearing 
  up 
  weeds 
  and 
  grasses 
  it 
  has 
  become 
  a 
  very 
  power- 
  

   ful 
  tearing 
  structure. 
  In 
  Cygnus 
  buccinator, 
  for 
  example, 
  the 
  

   edges 
  of 
  the 
  median 
  groove 
  instead 
  of 
  consisting 
  of 
  rather 
  rounded 
  

   eminences 
  become 
  very 
  sharp, 
  long 
  tearing 
  spines. 
  

  

  A 
  similar 
  purpose 
  is 
  accomplished 
  by 
  Branta 
  nigricans 
  by 
  con- 
  

   version 
  of 
  the 
  entire 
  lateral 
  row 
  of 
  hairs 
  into 
  spines 
  ; 
  in 
  other 
  words, 
  

   all 
  of 
  the 
  lateral 
  hairs 
  have 
  become 
  agglutinated 
  into 
  spines, 
  and 
  this 
  

   process 
  extends 
  quite 
  to 
  the 
  tip. 
  

  

  On 
  the 
  other 
  hand 
  the 
  red-breasted 
  merganser 
  (fig. 
  10), 
  having 
  

   taken 
  to 
  fish 
  fare, 
  has 
  developed 
  sharp 
  dorsal 
  spines 
  and 
  lost 
  one 
  

   row 
  of 
  marginal 
  hairs, 
  tending 
  to 
  approach 
  in 
  type 
  the 
  fish 
  eaters. 
  

  

  