﻿HOW 
  INSECTS 
  FLY 
  — 
  SNODGRASS 
  

  

  393 
  

  

  itiis, 
  and 
  for 
  this 
  reason 
  Tillj^ard 
  (1919) 
  has 
  renamed 
  it 
  the 
  second 
  

   branch 
  of 
  the 
  cubitus, 
  and 
  Karny 
  (1925) 
  terms 
  it 
  the 
  cubital 
  sector. 
  

   In 
  other 
  insects, 
  however, 
  the 
  sam.e 
  vein 
  apparently 
  has 
  no 
  basal 
  

   connections 
  in 
  the 
  adult 
  wing, 
  and 
  the 
  writer 
  (1929), 
  for 
  convenience, 
  

   has 
  called 
  it 
  the 
  second 
  cubitus. 
  (Fig. 
  10 
  B, 
  2Cu.) 
  In 
  any 
  case, 
  this 
  

   vein 
  has 
  no 
  relationship 
  with 
  the 
  other 
  so-called 
  anal 
  veins; 
  the 
  latter 
  

  

  C 
  Sc-i 
  Sc2 
  

  

  3A 
  2A 
  lA 
  

  

  tg- 
  HP 
  

  

  nV 
  2V 
  

  

  K;gube 
  10.— 
  The 
  veins 
  and 
  articular 
  scleritcs 
  of 
  the 
  wing 
  of 
  an 
  insect; 
  that 
  folds 
  the 
  wings 
  hori- 
  

   Kontally 
  over 
  the 
  back. 
  A, 
  Diagram 
  of 
  a 
  wing 
  with 
  the 
  veins 
  named 
  according 
  to 
  the 
  Coiu- 
  

   .Mtock-Needham 
  system; 
  lA, 
  iA, 
  first 
  and 
  second 
  anal 
  veins; 
  C, 
  costa; 
  Cu, 
  cubitus; 
  Cu\, 
  Cut, 
  

   branches 
  of 
  cubitus; 
  h, 
  humeral 
  cross 
  vein; 
  M, 
  media; 
  Mi-Mi, 
  branches 
  of 
  media; 
  m-cu, 
  

   medio-cubital 
  cross 
  vein; 
  m-m, 
  median 
  cross 
  vein; 
  R, 
  radius; 
  R,, 
  radial 
  sector; 
  Ri-Ri, 
  

   branches 
  of 
  radius; 
  r, 
  radial 
  cross 
  vein; 
  Sc, 
  subcosta; 
  Sc\-Sc2, 
  branches 
  of 
  subcosta. 
  B, 
  

   Nomenclature 
  of 
  the 
  veins 
  and 
  articular 
  sclerites 
  used 
  in 
  this 
  paper; 
  lAx, 
  2 
  Ax, 
  3Ax, 
  iAz, 
  

   first, 
  second, 
  third, 
  and 
  fourth 
  axillary 
  sclerites; 
  ICii, 
  first 
  cubitus 
  (Cu 
  of 
  A); 
  ^Ca, 
  second 
  

   cubitus 
  (lA 
  of 
  A); 
  HP, 
  humeral 
  plate; 
  ;,', 
  jugai 
  fold, 
  pHca 
  jugalis; 
  Ju, 
  jugal 
  region; 
  / 
  V, 
  first 
  

   vannal 
  vein 
  {2 
  A 
  of 
  A); 
  S 
  V-n 
  V, 
  second 
  to 
  last 
  vannal 
  veins; 
  tg, 
  rudiment 
  of 
  tegula; 
  Va, 
  vena 
  

   areuata; 
  Vc, 
  vena 
  cardinalis; 
  »/, 
  vannal 
  fold, 
  plica 
  vannalis 
  

  

  (lig. 
  10 
  A, 
  ^/l, 
  8A, 
  etc.) 
  constitute 
  a 
  natural 
  group 
  of 
  veins 
  in 
  the 
  

   posterior 
  part 
  of 
  the 
  wing 
  associated 
  with 
  the 
  third 
  articular 
  sclerite 
  

   of 
  the 
  wing 
  base 
  (B, 
  ZAx). 
  Since 
  the 
  wing 
  area 
  supported 
  by 
  these 
  

   veins 
  is 
  often 
  expanded 
  into 
  a 
  large, 
  fanlike 
  region, 
  the 
  writer 
  (1929) 
  

   has 
  suggested 
  calling 
  the 
  veins 
  of 
  this 
  region 
  the 
  vannal 
  veins 
  (Latin 
  

  

  