﻿322 
  C. 
  F. 
  M. 
  SWYNNERTON. 
  

  

  This 
  dominates 
  on 
  the 
  higher 
  hills, 
  as 
  on 
  Ngasamo 
  and 
  on 
  the 
  Ushashi 
  plateau, 
  and 
  is 
  

   far 
  more 
  freely 
  intermixed 
  with 
  broad-leaved 
  trees 
  than 
  any 
  of 
  the 
  others. 
  On 
  the 
  

   Ushashi 
  plateau 
  the 
  broad-leaved 
  trees 
  predominate 
  and, 
  with 
  a 
  Combretum 
  (near 
  

   telraphylhim, 
  Diels) 
  as 
  their 
  commonest 
  element, 
  they 
  include 
  also 
  such 
  trees 
  and 
  shrubs 
  

   as 
  Erythrina 
  tomentosa.R. 
  Br., 
  Kigelia, 
  Anona,Cussonia, 
  Grewia, 
  Rhus 
  glaucescens, 
  Rich., 
  

   Rhoicissus, 
  Parinarium, 
  and 
  two 
  species 
  of 
  Vitex. 
  This 
  bush 
  is 
  in 
  places 
  sufficiently 
  

   close 
  to 
  make 
  one 
  marvel 
  (in 
  spite 
  of 
  the 
  relatively 
  high 
  elevation) 
  at 
  the 
  absence 
  of 
  fly 
  

   and 
  the 
  presence 
  in 
  it 
  of 
  numerous 
  cattle. 
  It 
  is 
  very 
  distinct 
  from 
  anything 
  else 
  seen 
  on 
  

   this 
  safari. 
  The 
  granite 
  heads 
  that 
  here 
  and 
  there 
  project 
  are 
  densely 
  thicketed, 
  but 
  

   old 
  euphorbia 
  hedges 
  indicate 
  that 
  the 
  country 
  was 
  once 
  more 
  densely 
  settled 
  than 
  now. 
  

  

  (c) 
  The 
  formation 
  of 
  the 
  most 
  xerophilous 
  of 
  the 
  acacias 
  — 
  the 
  grey-leaved 
  ' 
  ' 
  mhali 
  " 
  

   {Acacia 
  spirocarpa, 
  Hochst.), 
  often 
  with 
  rock 
  below 
  and 
  therefore 
  somewhat 
  liable 
  to 
  

   water-logging 
  in 
  the 
  rains 
  and 
  an 
  extreme 
  of 
  dryness 
  in 
  the 
  dry 
  season. 
  This 
  type 
  

   clothes 
  the 
  ground 
  round 
  and 
  between 
  the 
  granite 
  kopjes 
  and 
  (interspersed 
  somewhat 
  

   with 
  mgongwa) 
  forms 
  (i) 
  extensive 
  fly-infested 
  forest 
  on 
  poor, 
  sandy, 
  badly-grassed 
  

   granite 
  soil 
  in 
  Nasa 
  and 
  Msanza 
  Mdogo 
  (PL 
  xii, 
  fig. 
  2), 
  and 
  (ii) 
  similar 
  forest, 
  but 
  

   without 
  fly, 
  in 
  granite 
  country 
  at 
  the 
  back 
  of 
  Musoma. 
  

  

  (d) 
  The 
  swamp-fringing 
  acacia, 
  the 
  " 
  ilula 
  " 
  (Acacia 
  drepanolobium, 
  Harms, 
  and 
  

   an 
  allied 
  species), 
  a 
  small, 
  straight, 
  often 
  unbranching 
  tree, 
  its 
  twigs 
  studded 
  with 
  

   large 
  round 
  galls 
  that 
  house 
  ants 
  ot 
  the 
  genus 
  Cremastogaster, 
  grows 
  somewhat 
  

   densely, 
  yet 
  without 
  giving 
  much 
  shade, 
  on 
  the 
  margins 
  of 
  the 
  seasonally-wet 
  

   mbugas. 
  It 
  is 
  sometimes 
  associated 
  with 
  a 
  Combretum 
  of 
  the 
  tetraphyllum 
  type 
  

   (as 
  in 
  PI. 
  xiv, 
  fig. 
  1) 
  and 
  ventures, 
  in 
  clumps, 
  into 
  parts 
  of 
  the 
  mbuga 
  itself. 
  

  

  (e) 
  The 
  larger, 
  shadier, 
  blacker-foliaged 
  " 
  tulangoi 
  "(Acacia 
  hebeoladoides 
  

   ttsambarensis, 
  Harms). 
  This 
  may 
  be 
  associated 
  with 
  the 
  ilula, 
  or 
  with 
  the 
  margins 
  of 
  

   ill-drained 
  spots 
  on 
  the 
  borders 
  of 
  mgu 
  country, 
  or 
  it 
  may 
  itself, 
  more 
  rarely, 
  locally 
  

   dominate. 
  In 
  the 
  latter 
  event 
  it 
  tends, 
  I 
  think, 
  to 
  be 
  rather 
  specially 
  associated 
  

   with 
  tsetse. 
  

  

  The 
  acacias 
  (regarded 
  alone- 
  — 
  for 
  I 
  have 
  yet 
  to 
  touch 
  on 
  thickets) 
  form 
  open 
  to 
  

   fairly 
  open 
  wooding, 
  and 
  are 
  high 
  where 
  there 
  has 
  been 
  no 
  recent 
  cultivation, 
  low 
  

   and 
  scrubby 
  (but 
  growing 
  up) 
  on 
  the 
  sites 
  of 
  abandoned 
  fields. 
  Their 
  most 
  widely 
  

   distributed 
  associate, 
  rather 
  linking 
  the 
  mhali 
  and 
  the 
  ilula 
  in 
  its 
  tastes 
  but 
  occurring 
  

   also 
  with 
  the 
  mgongwa, 
  is 
  another 
  of 
  the 
  Mimoseae 
  — 
  the 
  "mpogoro" 
  (Albizzia 
  

   hypoleitca, 
  Oliver) 
  ; 
  while 
  a 
  small 
  stubby 
  tree, 
  the 
  " 
  tinji 
  " 
  (Odina 
  sp. 
  ?), 
  an 
  early 
  

   leaf-shedder, 
  was 
  abundant 
  on 
  many 
  vlei 
  edges, 
  being 
  more 
  daring 
  in 
  the 
  matter 
  of 
  

   badly 
  drained 
  moisture 
  than 
  the 
  mpogoro 
  or 
  mhali, 
  yet 
  less 
  so 
  than 
  the 
  ilula. 
  It 
  is 
  

   always 
  gregarious, 
  but 
  it 
  may 
  be 
  found 
  in 
  association 
  with 
  any 
  of 
  these 
  species 
  or 
  

   bordering 
  a 
  swamp 
  itself. 
  The 
  fly 
  had 
  already 
  left 
  it 
  in 
  June. 
  

  

  (2) 
  Fringing 
  Forest. 
  — 
  To 
  be 
  distinguished 
  from 
  the 
  foregoing 
  tolerators 
  of 
  relatively 
  

   ill-drained 
  ground 
  are 
  the 
  true 
  (albeit 
  secondary) 
  fringing 
  formations 
  of 
  the 
  lake 
  

   and 
  the 
  rivers, 
  and 
  in 
  particular 
  the 
  rather 
  fine 
  fringing 
  savannah 
  forest 
  that 
  is 
  

   dominated 
  by 
  the 
  tall 
  and 
  handsome 
  "mgu" 
  (Acacia 
  campylocaniha, 
  Hochst.) 
  (PI. 
  

   xiv, 
  fig. 
  2). 
  This 
  grows 
  on 
  deeply 
  cracking 
  cotton 
  soil 
  that 
  is 
  liable 
  to 
  be 
  extensively 
  

   flooded 
  in 
  the 
  heaviest 
  rains, 
  and 
  that 
  even 
  in 
  June, 
  though 
  dry, 
  stood 
  out 
  as 
  a 
  bright 
  

   green 
  ribbon 
  of 
  tall, 
  coarse 
  grasses 
  ; 
  it 
  thus 
  contrasted 
  sharply 
  in 
  the 
  distance 
  with 
  the 
  

   dry 
  reddish 
  grass 
  of 
  the 
  adjacent 
  mhali 
  formation, 
  and 
  along 
  the 
  lower 
  reaches 
  of 
  

   the 
  Duma 
  in 
  particular 
  was 
  two 
  miles 
  or 
  more 
  in 
  breadth. 
  

  

  The 
  other 
  fringing 
  formations 
  are 
  (a) 
  the 
  mixture 
  of 
  ambatch, 
  Grewia, 
  Hibiscus, 
  

   reeds 
  and 
  papyrus 
  that 
  covers 
  the 
  broad 
  Simiyu 
  delta 
  in 
  Magu 
  Bay 
  and 
  (papyrus 
  

   chiefly) 
  partly 
  blocks 
  the 
  mouths 
  of 
  the 
  other 
  large 
  rivers 
  ; 
  (b) 
  the 
  close 
  fringe 
  or 
  

   hedge 
  of 
  bushy 
  Vernoni 
  as 
  (?) 
  that, 
  below 
  the 
  upper 
  bank, 
  lines 
  the 
  rivers 
  along 
  sandy 
  

   reaches, 
  and 
  appears 
  in 
  Plate 
  xv, 
  fig. 
  1, 
  in 
  its 
  usual 
  position 
  in 
  relation 
  to 
  the 
  heavier 
  

   wooding 
  ; 
  and 
  (c) 
  the 
  combination 
  of 
  fine 
  mgu 
  acacias, 
  large, 
  shady 
  Ficus 
  and 
  dense 
  

   under-shrubs 
  (same 
  Plate 
  and 
  figure) 
  that 
  tends 
  to 
  reproduce 
  the 
  shelter-conditions 
  

   of 
  primary 
  forest 
  and 
  should, 
  and 
  on 
  some 
  rivers 
  does, 
  harbour 
  G. 
  brevipalpis. 
  

  

  