﻿59 
  

  

  THE 
  EARLY 
  STAGES 
  OF 
  WEST 
  AFRICAN 
  MOSQUITOS— 
  IV. 
  

  

  By 
  A. 
  Ingram, 
  M.D., 
  CM., 
  and 
  J. 
  W. 
  S. 
  Macfie, 
  M.A., 
  D.Sc, 
  

  

  West 
  African 
  Medical 
  Service. 
  

  

  In 
  three 
  previous 
  papers 
  (Bull. 
  Ent. 
  Res. 
  vii, 
  pp. 
  1-18 
  ; 
  viii, 
  pp. 
  73-91 
  ; 
  and 
  

   viii, 
  pp. 
  135-154) 
  we 
  have 
  described 
  early 
  stages 
  of 
  a 
  number 
  of 
  West 
  African 
  

   mosquitos 
  collected 
  at 
  Accra 
  and 
  at 
  other 
  places 
  in 
  the 
  Gold 
  Coast. 
  The 
  present 
  

   paper 
  deals 
  with 
  a 
  few 
  more 
  early 
  stages 
  of 
  mosquitos, 
  for 
  the 
  most 
  part 
  collected 
  

   by 
  one 
  of 
  us 
  (A.I.) 
  in 
  the 
  Northern 
  Territories 
  of 
  the 
  Gold 
  Coast, 
  and 
  thus 
  fills 
  in 
  

   a 
  gap 
  or 
  two 
  in 
  the 
  knowledge 
  of 
  the 
  life-histories 
  of 
  these 
  insects. 
  

  

  The 
  majority 
  of 
  the 
  descriptions 
  which 
  follow 
  are 
  of 
  pupae. 
  As 
  in 
  our 
  previous 
  

   paper 
  we 
  have 
  taken 
  for 
  diagnostic 
  purposes 
  more 
  particularly 
  the 
  characters 
  

   of 
  the 
  paddles, 
  and 
  the 
  hairs 
  or 
  setae 
  at 
  the 
  posterior 
  angles 
  and 
  on 
  the 
  

   dorsal 
  aspect 
  of 
  the 
  abdominal 
  segments. 
  On 
  the 
  dorsal 
  aspect 
  and 
  at 
  

   the 
  posterior 
  margins 
  of 
  the 
  segments 
  of 
  the 
  abdomen 
  there 
  are 
  important 
  

   hairs 
  which 
  form 
  two 
  distinct 
  rows 
  on 
  each 
  side 
  of 
  the 
  body 
  from 
  usually 
  the 
  3rd 
  

   to 
  the 
  7th 
  segments. 
  The 
  one 
  row 
  is 
  situated 
  midway 
  between 
  the 
  posterior 
  angles 
  

   and 
  the 
  middle 
  line 
  of 
  the 
  body, 
  the 
  other 
  about 
  midway 
  between 
  the 
  posterior 
  

   angles 
  and 
  the 
  first 
  row. 
  These 
  two 
  rows 
  of 
  hairs 
  do 
  not 
  appear 
  to 
  have 
  received 
  

   names, 
  we 
  therefore 
  propose 
  to 
  call 
  them 
  respectively 
  the 
  " 
  inner 
  and 
  outer 
  lateral 
  

  

  rows. 
  " 
  

  

  We 
  have 
  found 
  it 
  advisable 
  to 
  introduce 
  into 
  the 
  descriptions 
  of 
  pupae 
  certain 
  

   ratios, 
  such 
  as 
  the 
  ratio 
  of 
  length 
  to 
  greatest 
  breadth 
  of 
  the 
  paddles 
  or 
  respiratory 
  

   trumpets. 
  The 
  respiratory 
  trumpet 
  is 
  composed 
  of 
  two 
  parts, 
  a 
  closed 
  or 
  tubular 
  

   part 
  which 
  is 
  proximal, 
  and 
  an 
  open 
  part 
  which 
  is 
  distal 
  ; 
  the 
  former 
  we 
  propose 
  

   to 
  call 
  the 
  meatus, 
  and 
  the 
  latter 
  the 
  pinna. 
  The 
  relative 
  length 
  of 
  the 
  meatus 
  

   varies 
  greatly 
  in 
  different 
  species 
  of 
  mosquito, 
  and 
  this 
  fact 
  we 
  think 
  may 
  be 
  most 
  

   accurately 
  expressed 
  as 
  the 
  ratio 
  of 
  the 
  length 
  of 
  the 
  meatus 
  to 
  the 
  total 
  length 
  

   of 
  the 
  respiratory 
  trumpet. 
  

  

  Anopheles 
  pretoriensis, 
  Theo. 
  

  

  Larva. 
  — 
  The 
  larva 
  of 
  this 
  mosquito 
  is 
  included 
  by 
  Edwards 
  (Bull. 
  Ent. 
  Res. 
  

   hi, 
  p. 
  374) 
  in 
  his 
  key 
  to 
  the 
  larvae 
  of 
  the 
  genus 
  Anopheles. 
  

  

  Pupa 
  (fig. 
  1). 
  — 
  The 
  pupa 
  is 
  small, 
  measuring 
  about 
  4 
  mm. 
  when 
  extended, 
  

   and 
  feebly 
  chitinised. 
  

  

  The 
  paddles, 
  which 
  are 
  about 
  '7 
  mm. 
  long, 
  are 
  oval, 
  the 
  ratio 
  of 
  length 
  to 
  greatest 
  

   breadth 
  being 
  about 
  1*6 
  to 
  1 
  ; 
  they 
  are 
  furnished 
  with 
  a 
  midrib, 
  and 
  an 
  external 
  

   buttress 
  which 
  does 
  not 
  seem 
  to 
  extend 
  beyond 
  the 
  proximal 
  third 
  of 
  the 
  blade. 
  

   The 
  hook-shaped 
  hair 
  on 
  the 
  distal 
  edge 
  of 
  the 
  paddle 
  is 
  well 
  developed 
  and 
  about 
  

   half 
  the 
  length 
  of 
  the 
  paddle 
  ; 
  proximal 
  to 
  it, 
  near 
  the 
  end 
  of 
  the 
  midrib, 
  is 
  a 
  

   short 
  straight 
  hair 
  which 
  is 
  forked 
  almost 
  from 
  its 
  base, 
  and 
  is 
  about 
  one-sixth 
  

   the 
  length 
  of 
  the 
  hook-shaped 
  hair. 
  The 
  paddles 
  carry 
  a 
  fringe 
  of 
  rather 
  delicate 
  

   hairs, 
  longest 
  on 
  the 
  distal 
  border 
  ; 
  this 
  fringe 
  appears 
  to 
  begin 
  at 
  a 
  point 
  beyond 
  

   the 
  middle 
  of 
  the 
  external 
  border. 
  

  

  