﻿328 
  C. 
  F. 
  M. 
  SWYNNERTON. 
  

  

  The 
  fly 
  area 
  shown 
  in 
  the 
  map 
  south-east 
  of 
  Shirati 
  is 
  one 
  of 
  pallidipes, 
  Dr. 
  J. 
  B. 
  

   Davey 
  having 
  taken 
  this 
  fly 
  in 
  small 
  numbers 
  in 
  country 
  that 
  was 
  on 
  the 
  whole 
  open 
  

   and 
  in 
  which 
  numerous 
  cattle 
  were 
  present 
  from 
  Bukina 
  (two 
  hours 
  from 
  Shirati) 
  

   to 
  Kinesi. 
  Dr. 
  Beven 
  (unpublished 
  report) 
  found 
  it 
  in 
  dry 
  thorn 
  bush 
  (1) 
  with 
  G. 
  

   fusca, 
  along 
  the 
  south 
  bank 
  of 
  the 
  Kuja 
  River, 
  some 
  distance 
  from 
  the 
  water, 
  from 
  

   near 
  Welbondo 
  to 
  a 
  short 
  way 
  beyond 
  the 
  Gori 
  ; 
  (2) 
  in 
  Kasiganga, 
  between 
  

   Nyangoma 
  and 
  Moita, 
  in 
  numbers 
  that 
  precluded 
  the 
  keeping 
  of 
  cattle 
  ; 
  (3) 
  heard 
  

   of 
  only, 
  probably 
  this 
  species, 
  in 
  the 
  Lambwa 
  valley. 
  I 
  have 
  already 
  referred 
  to 
  

   the 
  Isuria-Mara 
  belt. 
  

  

  It 
  will 
  be 
  noted 
  that 
  we 
  first 
  met 
  G. 
  pallidipes 
  on 
  reaching 
  the 
  border 
  line 
  (a) 
  of 
  

   a 
  better 
  rainfall 
  area; 
  (b) 
  of 
  a 
  less 
  xerophytic 
  vegetation; 
  and 
  (c), 
  perhaps 
  only 
  

   indirectly 
  important, 
  of 
  a 
  more 
  mountainous 
  area. 
  

  

  5. 
  Glossina 
  swynnertoni, 
  Austen. 
  

  

  The 
  only 
  tsetse 
  that 
  could 
  anywhere 
  be 
  found 
  in 
  the 
  known 
  infected 
  area 
  by 
  a 
  

   most 
  thorough 
  search, 
  stimulated 
  by 
  means 
  of 
  rewards 
  and 
  carried 
  out 
  by 
  a 
  large 
  

   number 
  of 
  natives 
  and, 
  in 
  all, 
  30 
  bait-cattle, 
  and 
  the 
  only 
  fly 
  that 
  had 
  been 
  taken 
  

   therein 
  previously 
  to 
  my 
  arrival, 
  was 
  a 
  species 
  of 
  the 
  morsitans 
  group. 
  

  

  This 
  tsetse, 
  referred 
  to 
  hereinafter 
  as 
  " 
  the 
  fly," 
  has 
  been 
  named 
  by 
  Mr. 
  Austen 
  

   after 
  myself 
  as 
  this 
  paper 
  goes 
  to 
  press. 
  I 
  greatly 
  appreciate 
  the 
  linking 
  of 
  my 
  name 
  

   with 
  a 
  subject 
  in 
  which 
  I 
  am 
  so 
  keenly 
  interested, 
  but 
  I 
  can 
  lay 
  no 
  claim 
  to 
  having 
  

   first 
  taken 
  the 
  fly. 
  The 
  Germans 
  took 
  it 
  for 
  G. 
  morsitans 
  ; 
  Mr. 
  Fiske 
  told 
  me 
  that 
  

   he 
  took 
  numbers, 
  presumably 
  of 
  this 
  fly, 
  at 
  Nasa 
  over 
  two 
  years 
  ago 
  ; 
  and 
  the 
  earliest 
  

   flies 
  now 
  in 
  my 
  possession 
  were 
  captured 
  by 
  Mr. 
  G. 
  G. 
  Griffiths 
  in 
  the 
  Seke-Chinyanga 
  

   belt 
  early 
  in 
  March 
  of 
  this 
  year. 
  Dr. 
  Maclean, 
  the 
  discoverer 
  of 
  the 
  outbreak, 
  and, 
  

   helping 
  him, 
  Mr. 
  Tully 
  and 
  (I 
  believe) 
  the 
  Administrative 
  Officers, 
  also 
  took 
  many 
  

   in 
  that 
  and 
  the 
  following 
  month. 
  

  

  It 
  is 
  nearest 
  to 
  G. 
  morsitans, 
  though 
  in 
  certain 
  characters, 
  both 
  in 
  the 
  adult 
  fly 
  

   and 
  the 
  pupa, 
  it 
  resembles 
  the 
  flies 
  of 
  the 
  pallidipes 
  sub-group. 
  It 
  does 
  so 
  also 
  in 
  

   its 
  preference 
  for 
  breeding 
  in 
  thickets 
  of 
  the 
  type 
  frequented 
  by 
  pallidipes 
  (v. 
  p. 
  333). 
  

   It 
  resembles 
  G. 
  morsitans 
  in 
  its 
  savage 
  attachment 
  to 
  man, 
  in 
  the 
  relative 
  absence 
  

   of 
  game. 
  I 
  have 
  seen 
  no 
  tsetse 
  that 
  so 
  readily 
  attacks 
  man 
  with 
  cattle 
  present, 
  

   and 
  no 
  fly 
  the 
  females 
  of 
  which 
  travel 
  so 
  freely 
  and 
  far 
  on 
  man. 
  Both 
  traits 
  were 
  

   undoubtedly 
  due 
  largely 
  to 
  the 
  fact 
  that 
  in 
  the 
  places 
  in 
  which 
  they 
  were 
  specially 
  

   prominent 
  man 
  had 
  successfully 
  replaced 
  the 
  game 
  as 
  the 
  fly's 
  chief 
  food-animal. 
  

   In 
  the 
  order 
  of 
  readiness 
  to 
  attack 
  man 
  the 
  tsetse 
  on 
  which 
  I 
  have 
  done 
  most 
  

   work 
  may 
  be 
  ranged 
  thus 
  : 
  (1) 
  G. 
  swynnertoni 
  ; 
  (2) 
  G. 
  morsitans 
  ; 
  (3) 
  G. 
  pallidipes 
  ; 
  

   (4) 
  G. 
  brevipalpis 
  ; 
  (5) 
  G. 
  austeni. 
  

  

  From 
  what 
  I 
  have 
  read 
  of 
  G. 
  palpalis 
  rather 
  than 
  from 
  my 
  very 
  few 
  days' 
  work 
  

   on 
  it 
  (on 
  Lake 
  Tanganyika, 
  in 
  particular), 
  I 
  would 
  bracket 
  it 
  with 
  the 
  first 
  two 
  of 
  

   these 
  species. 
  

  

  G. 
  swynnertoni 
  inhabits, 
  to 
  the 
  exclusion 
  of 
  G. 
  morsitans, 
  a 
  solid 
  tract 
  of 
  country 
  that 
  

   is 
  cut 
  off 
  from 
  a 
  partly 
  surrounding 
  arc 
  of 
  pure 
  G. 
  morsitans 
  by 
  a 
  strip 
  of 
  native 
  culti- 
  

   vation, 
  and 
  it 
  may 
  prove 
  to 
  come 
  into 
  contact 
  with 
  the 
  latter 
  fly 
  east 
  of 
  Chinyanga 
  

   or 
  on 
  the 
  Nanga. 
  It 
  is 
  remarkably 
  unvarying 
  in 
  appearance 
  and 
  in 
  its 
  genitalia, 
  

   and 
  G. 
  morsitans 
  (as 
  my 
  material 
  shows) 
  varies 
  much 
  even 
  in 
  single 
  localities, 
  an 
  

   extreme 
  form 
  showing 
  an 
  approach 
  to 
  this 
  fly 
  in 
  colour-pattern, 
  though 
  not 
  in 
  

   colour. 
  It 
  looks 
  like 
  a 
  case 
  in 
  which 
  a 
  variety 
  has 
  become 
  fixed 
  as 
  a 
  species 
  through 
  

   long 
  isolation. 
  On 
  the 
  other 
  hand, 
  the 
  occurrence 
  of 
  an 
  unvarying 
  fly 
  possessing 
  

   characters 
  in 
  common 
  with 
  pallidipes 
  on 
  the 
  border 
  that 
  finally, 
  on 
  the 
  north-east, 
  

   separates 
  the 
  distribution 
  of 
  much- 
  varying 
  G. 
  morsitans 
  from 
  the 
  unmixed 
  distribution 
  

   of 
  relatively 
  unvarying 
  G. 
  pallidipes, 
  suggests 
  a 
  greater 
  age 
  for 
  it, 
  and 
  this 
  view 
  is 
  

   supported 
  further 
  by 
  the 
  consideration 
  that 
  the 
  barrier 
  of 
  native 
  settlement 
  that 
  

   in 
  one 
  part 
  only 
  slightfy, 
  and 
  perhaps 
  not 
  entirely, 
  separates 
  the 
  two 
  flies 
  can 
  hardly 
  

   be 
  of 
  such 
  age 
  as 
  to 
  have 
  brought 
  about 
  the 
  fixing 
  of 
  a 
  species. 
  

  

  