﻿27.— 
  A 
  PRELIMINARY 
  NOTE 
  ON 
  NEW 
  THORACIC 
  APPENDAGES 
  

   IN 
  ANOPHELINE 
  LARV^. 
  

  

  (Plate 
  XXXVIII). 
  

  

  By 
  M. 
  0. 
  TiRUNARAYANA 
  IYENGAR, 
  B.A., 
  Entomologist, 
  Bengal 
  Malaria 
  

  

  Research. 
  

  

  A 
  paired 
  contractile 
  appendage 
  has 
  been 
  observed 
  on 
  the 
  dorsal 
  

   anterior 
  region 
  of 
  the 
  thorax 
  of 
  the 
  Anopheles 
  larva, 
  the 
  structure, 
  

   position 
  and 
  movement 
  of 
  which 
  are 
  herein 
  described. 
  The 
  appendage 
  

   has 
  a 
  basal 
  pedicel 
  which 
  is 
  produced 
  apically 
  into 
  two 
  finger-like 
  lobes. 
  

   Each 
  of 
  these 
  lobes 
  is 
  provided 
  with 
  a 
  thin 
  lamellar 
  expansion 
  of 
  the 
  

   cuticle 
  as 
  seen 
  in 
  Plate 
  XXXVIII 
  fig. 
  2a. 
  The 
  appendage 
  is 
  provided 
  

   with 
  a 
  muscle 
  which 
  is 
  attached 
  to 
  the 
  cuticular 
  region 
  between 
  the 
  

   two 
  lobes, 
  and 
  when 
  the 
  muscle 
  contracts, 
  the 
  lobes 
  move 
  towards 
  

   each 
  other. 
  But 
  it 
  usually 
  contracts 
  to 
  a 
  much 
  greater 
  extent, 
  and 
  as 
  

   a 
  result 
  the 
  whole 
  appendage 
  is 
  withdrawn 
  into 
  the 
  thorax. 
  This 
  very 
  

   rapid 
  movement 
  is 
  quite 
  frequent 
  and 
  can 
  be 
  seen 
  in 
  living 
  larvae 
  

   especially 
  of 
  those 
  of 
  Anopheles 
  sinensis 
  or 
  A. 
  harhirostris 
  in 
  which 
  

   species 
  these 
  appendages 
  are 
  well 
  developed. 
  

  

  In 
  the 
  normal 
  position 
  of 
  the 
  larva, 
  the 
  appendages 
  cannot 
  be 
  fully 
  

   seen 
  as 
  only 
  the 
  tips 
  of 
  the 
  lobes 
  can 
  be 
  seen 
  protruding 
  beyond 
  the 
  

   profile 
  of 
  the 
  thorax 
  even 
  in 
  the 
  best 
  developed 
  forms. 
  If 
  however 
  a 
  

   cover-glass 
  is 
  dropped 
  lightly 
  on 
  the 
  larva 
  and 
  by 
  a 
  slight 
  movement 
  of 
  

   the 
  cover-glass 
  the 
  larva 
  is 
  turned 
  to 
  one 
  side 
  the 
  whole 
  appendage 
  

   would 
  come 
  into 
  view 
  and 
  the 
  details 
  of 
  its 
  structure 
  can 
  then 
  be 
  made 
  

   out. 
  It 
  frequently 
  happens 
  that 
  the 
  whole 
  appendage 
  is 
  withdrawn 
  into 
  

   the 
  thorax. 
  In 
  such 
  a 
  case, 
  nothing 
  can 
  be 
  seen 
  except 
  a 
  depression 
  in 
  

   the 
  thorax, 
  and 
  to 
  see 
  the 
  appendage 
  it 
  will 
  be 
  necessary 
  to 
  wait 
  till 
  the 
  

   contracted 
  muscle 
  relaxes 
  again 
  and 
  the 
  appendage 
  is 
  exerted. 
  To 
  have 
  

   a 
  clear 
  view 
  of 
  the 
  cuticular 
  lamina 
  of 
  the 
  lobes 
  it 
  would 
  be 
  necessary 
  

   to 
  use 
  a 
  very 
  low 
  illumination. 
  They 
  are 
  highly 
  transparent 
  and 
  are 
  

   wedgeshaped 
  when 
  seen 
  edge-wise. 
  

  

  The 
  muscle 
  controlling 
  the 
  movement 
  of 
  the 
  appendage 
  is 
  a 
  long 
  

   transverse 
  one 
  starting 
  from 
  the 
  sub-posterior 
  ventral 
  region 
  of 
  the 
  

   thorax 
  and 
  ending 
  at 
  the 
  dorsal 
  anterior 
  part 
  of 
  the 
  thorax 
  in 
  the 
  append- 
  

   ages. 
  The 
  appendages 
  themselves 
  seem 
  to 
  take 
  their 
  origin 
  from 
  the 
  

   anterior 
  sub-dorsal 
  region 
  of 
  the 
  meso-thorax 
  rather 
  than 
  from 
  the 
  pro- 
  

   thorax 
  which 
  is 
  very 
  small 
  in 
  comparison 
  with 
  the 
  mesothoracic 
  seg- 
  

   ment. 
  But 
  as 
  there 
  are 
  no 
  clear 
  lines 
  of 
  demarcation 
  between 
  the 
  

  

  ( 
  «6 
  ) 
  

  

  