﻿of 
  the 
  Bill 
  in 
  Birds. 
  363 
  

  

  specially 
  distinguished. 
  They 
  have 
  nevertheless 
  been 
  named 
  

   independently 
  and 
  by 
  several 
  writers, 
  each 
  of 
  whom 
  has 
  

   bestowed 
  a 
  difterent 
  name 
  upon 
  them. 
  This 
  fact 
  tends 
  to 
  

   confuse 
  the 
  subject 
  not 
  a 
  little. 
  As 
  a 
  case 
  in 
  point 
  I 
  may 
  

   mention 
  that 
  both 
  Owen 
  and 
  Dr. 
  Shufeldt 
  have 
  given 
  the 
  

   name 
  of 
  entotympanic 
  to 
  each 
  of 
  the 
  muscles 
  now 
  under 
  

   discussion, 
  yet 
  neither 
  had 
  the 
  same 
  muscle 
  in 
  view. 
  Owen^s 
  

   entotympanic 
  (or 
  entotympanicus, 
  to 
  be 
  quite 
  correct) 
  is 
  

   that 
  which 
  runs 
  from 
  the 
  basisphenoid 
  to 
  the 
  quadrate, 
  or 
  

   " 
  tympanic 
  " 
  as 
  he 
  calls 
  it, 
  whilst 
  that 
  of 
  Dr. 
  Shufeldt 
  runs 
  

   from 
  the 
  orbital 
  septum 
  to 
  the 
  pterygoid 
  *. 
  

  

  In 
  order 
  to 
  understand 
  how 
  this 
  particular 
  movement 
  is 
  

   brought 
  about, 
  it 
  is 
  necessary 
  to 
  bear 
  in 
  mind 
  that 
  the 
  distal 
  

   end 
  of 
  the 
  quadrate 
  articulates 
  on 
  its 
  outer 
  side 
  with 
  the 
  

   quadrato-jugal 
  bar, 
  on 
  its 
  inner 
  with 
  the 
  pterygoid, 
  and 
  that 
  

   this 
  in 
  turn 
  (the 
  pterygoid) 
  articulates 
  with 
  the 
  palatine 
  (PL), 
  

   the 
  distal 
  end 
  of 
  which, 
  together 
  with 
  that 
  of 
  the 
  quadrato- 
  

   jugal, 
  joins 
  the 
  premaxillary 
  bones. 
  Now, 
  on 
  the 
  contraction 
  

   of 
  the 
  muscles 
  in 
  question, 
  the 
  quadrate 
  and 
  pterygoid 
  bones 
  

   are 
  thrust 
  forwards, 
  and 
  with 
  them 
  all 
  the 
  bones 
  opposed 
  to 
  

   them 
  in 
  front 
  ; 
  at 
  the 
  trif 
  urcation 
  of 
  the 
  premaxilla 
  the 
  

   weakest 
  point 
  is 
  reached, 
  and 
  the 
  remainder 
  of 
  the 
  beak 
  

   curves 
  upwards. 
  In 
  ordinary 
  birds 
  under 
  similar 
  conditions 
  

   this 
  point 
  (the 
  weakest) 
  would 
  be 
  at 
  the 
  frontonasal 
  articu- 
  

   lation, 
  and 
  consequently 
  the 
  whole 
  jaw 
  would 
  be 
  raised, 
  

   instead 
  of 
  the 
  tip 
  only. 
  Perhaps 
  a 
  reference 
  to 
  the 
  figure 
  

   given 
  herewith 
  (p. 
  362) 
  will 
  assist 
  in 
  making 
  these 
  details 
  

   clearer. 
  

  

  Prof. 
  Huxley 
  attributes 
  the 
  raising 
  of 
  the 
  upper 
  jaw 
  to 
  

   the 
  contraction 
  of 
  the 
  digastric 
  muscle 
  f, 
  considering 
  that 
  

   on 
  the 
  opening 
  of 
  the 
  mouth 
  the 
  quadrate 
  would 
  be 
  thrust 
  

   forwards, 
  and 
  thus 
  it 
  will 
  be 
  noted 
  the 
  same 
  movements 
  will 
  be 
  

   set 
  up 
  as 
  those 
  which 
  I 
  have 
  described. 
  I 
  cannot 
  but 
  think, 
  

   though, 
  that 
  this 
  muscle 
  plays 
  a 
  secondary 
  part 
  in 
  the 
  system. 
  

  

  ♦ 
  Dr. 
  Shufeldt 
  is 
  describing 
  the 
  myology 
  of 
  the 
  head 
  of 
  the 
  Raven, 
  

   where 
  this 
  muscle 
  gives 
  off 
  a 
  tendinous 
  slip 
  to 
  the 
  distal 
  end 
  of 
  the 
  

   quadrate. 
  

  

  t 
  This 
  is 
  apparently 
  equivalent 
  to 
  the 
  human 
  digastric, 
  and 
  the 
  biventer 
  

   maxilUe 
  of 
  <,iadow, 
  Shufeldt, 
  and 
  Owen. 
  

  

  