﻿404 
  

  

  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  192 
  9 
  

  

  )ill 
  cases, 
  on 
  the 
  pleura 
  and 
  on 
  the 
  basal 
  segments, 
  or 
  coxse, 
  of 
  the 
  legs 
  

   (fig. 
  19, 
  Cx). 
  In 
  the 
  young 
  of 
  insects 
  that 
  resemble 
  the 
  adults 
  in 
  bodily 
  

   form, 
  however, 
  these 
  same 
  muscles 
  are 
  inserted 
  on 
  the 
  dorsal 
  edges 
  

   of 
  the 
  lateral 
  walls 
  of 
  the 
  wing-bearing 
  segments. 
  It 
  appears 
  highly 
  

   probable, 
  therefore, 
  that 
  the 
  coxal 
  basalar 
  and 
  subalar 
  wing 
  muscles 
  

   of 
  adult 
  insects 
  are 
  in 
  origin 
  leg 
  muscles 
  that 
  have 
  been 
  given 
  over 
  to 
  

   the 
  service 
  of 
  the 
  wings. 
  The 
  function 
  of 
  these 
  muscles 
  will 
  be 
  more 
  

  

  particularly 
  described 
  in 
  

   the 
  following 
  section. 
  

  

  The 
  muscle 
  of 
  the 
  basalar 
  

   sclerite 
  arising 
  on 
  the 
  coxa 
  

  

  ^§""1 
  ( 
  ' 
  k 
  l-^>^ 
  H^'^^Xs^ 
  (fig. 
  19, 
  MO 
  is 
  usually 
  sup- 
  

   plemented 
  by 
  a 
  branch 
  or 
  a 
  

   second 
  muscle 
  {E) 
  arising 
  

   on 
  the 
  lateral 
  wall 
  of 
  the 
  

   segment, 
  or 
  on 
  the 
  sternum. 
  

   The 
  basalar 
  sclerite, 
  as 
  we 
  

   have 
  seen, 
  is 
  intimately 
  at- 
  

   tached 
  to 
  the 
  humeral 
  angle 
  

   of 
  the 
  wing 
  base 
  by 
  a 
  

   thickening 
  (a) 
  of 
  the 
  inter- 
  

   vening 
  membrane. 
  The 
  

   subalar 
  muscle 
  (fig. 
  19, 
  M") 
  

   is 
  always 
  a 
  large 
  muscle, 
  

   and, 
  through 
  the 
  attach- 
  

   ment 
  (6) 
  of 
  the 
  subalar 
  scle- 
  

   rite 
  with 
  the 
  second 
  axillary 
  

   sclerite 
  of 
  the 
  wing 
  base 
  

   {2Ax) 
  it 
  pulls 
  downward 
  on 
  

   the 
  base 
  of 
  the 
  wing 
  imme- 
  

   diately 
  behind 
  the 
  fulcra! 
  

   support 
  {WP). 
  

  

  In 
  the 
  dragon 
  flies 
  the 
  

   homologues 
  of 
  the 
  basalar 
  

   and 
  subalar 
  muscles 
  of 
  

   other 
  insects 
  are 
  inserted 
  

   by 
  strong 
  "tendons" 
  

   that 
  are 
  attached 
  directly 
  

   on 
  the 
  wing 
  bases, 
  the 
  first 
  on 
  the 
  humeral 
  plate 
  (fig. 
  11 
  A, 
  HP) 
  

   the 
  second 
  on 
  the 
  axillary 
  plate 
  {AxP). 
  Furthermore, 
  the 
  ven- 
  

   tral 
  ends 
  of 
  these 
  muscles 
  in 
  the 
  dragon 
  flies 
  take 
  their 
  origin 
  on 
  the 
  

   lower 
  edge 
  of 
  the 
  pleural 
  wall 
  of 
  the 
  segment, 
  their 
  bases 
  evidently 
  

   having 
  been 
  transferred 
  from 
  the 
  coxa 
  to 
  the 
  body 
  wall. 
  In 
  the 
  flies 
  

   (Diptera) 
  the 
  base 
  of 
  the 
  subalar 
  muscle 
  has 
  undergone 
  a 
  similar 
  

   transposition. 
  

  

  pir: 
  

  

  Figure 
  19.— 
  The 
  pleural 
  wing 
  muscles 
  of 
  the 
  mesothorax 
  

   of 
  a 
  grasshopper 
  (Dmosieira), 
  inner 
  view 
  of 
  right 
  side. 
  

   a, 
  Membranous 
  connectioii 
  of 
  basalar 
  sclerites 
  (Ba) 
  with 
  

   humeral 
  angle 
  of 
  wing 
  base; 
  SAx, 
  dorsal 
  plate 
  of 
  second 
  

   axillary; 
  SAx, 
  third 
  axillary; 
  b, 
  connection 
  of 
  subaiare 
  (Sa) 
  

   with 
  second 
  axillary; 
  Ba, 
  basalar 
  sclerites; 
  c, 
  ventral 
  plate 
  of 
  

   .■second 
  axillary; 
  Cx, 
  coxa; 
  D, 
  flexor 
  muscle 
  of 
  wing; 
  E, 
  pleu- 
  

   ral 
  basalar 
  muscle; 
  M', 
  coxo-basalar 
  muscle; 
  M", 
  co\o-sub- 
  

   alar 
  muscle; 
  PIR, 
  pleural 
  rid^e; 
  Sa, 
  sulialare; 
  tg, 
  rudiment 
  

   oftegula; 
  If 
  3, 
  inesothoracic 
  wing, 
  turned 
  upward 
  

  

  