﻿296 
  S. 
  A. 
  NEAVE. 
  

  

  Nyasaland 
  : 
  Type 
  <J, 
  Mlanje, 
  28 
  x. 
  13 
  ; 
  type 
  $, 
  Ruo 
  R., 
  near 
  Mlanje, 
  25 
  x. 
  13 
  ; 
  

   and 
  133 
  other 
  <j>$ 
  from 
  the 
  same 
  localities. 
  

  

  This 
  striking 
  species 
  was 
  taken 
  in 
  some 
  numbers 
  between 
  the 
  13th 
  of 
  October 
  

   and 
  the 
  end 
  of 
  that 
  month. 
  From 
  that 
  time, 
  though 
  occasional 
  specimens 
  were 
  

   taken 
  up 
  to 
  the 
  middle 
  of 
  November, 
  it 
  became 
  very 
  scarce. 
  It 
  has 
  evidently 
  

   therefore 
  a 
  very 
  short 
  season, 
  and 
  this, 
  coupled 
  with 
  its 
  singular 
  habits 
  and 
  

   apparently 
  limited 
  distribution, 
  probably 
  explains 
  why 
  it 
  has 
  not 
  been 
  discovered 
  

   before. 
  I 
  found 
  it 
  only 
  in 
  the 
  Luchenya 
  and 
  Ruo 
  (see 
  PL 
  xxix, 
  fig. 
  2), 
  two 
  

   forested 
  rivers, 
  which 
  rise 
  on 
  Mt. 
  Mlanje. 
  It 
  did 
  not, 
  however, 
  occur 
  on 
  the 
  

   mountain 
  side, 
  only 
  in 
  the 
  more 
  forested 
  portions 
  of 
  the 
  rivers 
  where 
  they 
  had 
  

   debouched 
  into 
  comparatively 
  flat 
  country. 
  This 
  fly 
  was 
  never 
  seen 
  except 
  in 
  

   the 
  immediate 
  vicinity 
  of 
  these 
  rivers, 
  in 
  fact, 
  only 
  over 
  the 
  surface 
  of 
  the 
  water 
  

   or 
  on 
  the 
  actual 
  bank. 
  It 
  has 
  a 
  very 
  swift 
  and 
  powerful 
  flight, 
  and 
  was 
  

   only 
  captured 
  in 
  any 
  numbers 
  by 
  stationing 
  collectors 
  in 
  the 
  river 
  to 
  watch 
  

   projecting 
  rocks, 
  tree-trunks, 
  etc., 
  in 
  the 
  bed 
  of 
  the 
  stream 
  or 
  at 
  the 
  water's 
  edge, 
  

   points 
  where 
  it 
  had 
  a 
  habit 
  of 
  settling 
  at 
  intervals 
  for 
  a 
  second 
  or 
  two. 
  It 
  makes 
  

   a 
  very 
  deep 
  note 
  on 
  the 
  wing, 
  which 
  my 
  native 
  collectors 
  learnt 
  to 
  recognise 
  at 
  

   a 
  distance. 
  It 
  is 
  not 
  very 
  clear 
  what 
  animals 
  this 
  insect 
  feeds 
  on. 
  I 
  have 
  no 
  record 
  

   of 
  its 
  biting 
  man. 
  There 
  are 
  no 
  crocodiles 
  in 
  these 
  rivers, 
  at 
  least 
  on 
  the 
  part 
  of 
  

   them 
  in 
  question, 
  though 
  Varanus 
  lizards 
  are 
  common 
  and 
  there 
  are 
  a 
  few 
  

   hippopotami 
  in 
  the 
  Ruo. 
  

  

  Silvius 
  monticola, 
  sp. 
  nov. 
  

  

  A 
  rather 
  small 
  dusky 
  species 
  somewhat 
  resembling 
  in 
  appearance 
  S. 
  australis, 
  Ric, 
  

   from 
  North 
  Queensland, 
  Australia. 
  

  

  <J. 
  — 
  Length 
  (10 
  individuals), 
  8*4 
  mm. 
  ; 
  length 
  of 
  wing, 
  7*9 
  mm. 
  

  

  §. 
  — 
  Length 
  (10 
  individuals), 
  10/4 
  mm. 
  ; 
  length 
  of 
  wing, 
  10*3 
  mm. 
  

  

  $. 
  — 
  Head 
  with 
  the 
  front 
  narrow, 
  pale 
  buff 
  at 
  edges, 
  dusky 
  in 
  centre 
  ; 
  ocelli 
  and 
  the 
  

   narrow, 
  vertically 
  elongate 
  callus, 
  black 
  ; 
  palpi 
  short 
  and 
  covered 
  with 
  black 
  hairs 
  ; 
  

   antennae 
  (fig. 
  2, 
  b) 
  black, 
  the 
  first 
  two 
  joints 
  being 
  clothed 
  with 
  black 
  hair, 
  and 
  the 
  

   proximal 
  portion 
  of 
  the 
  3rd 
  joint 
  curiously 
  curved 
  (fig. 
  3 
  b). 
  Thorax 
  dusky, 
  with 
  two 
  

   evanescent 
  pale 
  buff 
  lines, 
  of 
  which 
  little 
  remains 
  in 
  most 
  individuals 
  but 
  two 
  

   triangular 
  patches 
  on 
  anterior 
  margin 
  ; 
  external 
  to 
  these 
  triangles 
  are 
  humeral 
  spots 
  

   of 
  the 
  same 
  colour. 
  Abdomen 
  black, 
  the 
  posterior 
  margin 
  of 
  each 
  segment 
  being 
  

   edged 
  with 
  pale 
  buff 
  (fig. 
  4). 
  Wings 
  hyaline, 
  somewhat 
  infuscated 
  at 
  base 
  and 
  

   along 
  costa. 
  Legs 
  black. 
  

  

  (J. 
  — 
  Smaller 
  than 
  the 
  $, 
  the 
  hair 
  on 
  the 
  peristome, 
  thorax, 
  etc., 
  being 
  buff 
  instead 
  

   of 
  black 
  ; 
  thorax 
  more 
  hairy 
  and 
  the 
  two 
  pale 
  thoracic 
  stripes 
  more 
  defined. 
  On 
  the 
  

   abdomen 
  the 
  pale 
  margins 
  to 
  the 
  segments 
  broader, 
  especially 
  at 
  the 
  sides 
  of 
  the 
  

   anterior 
  ones 
  ; 
  the 
  tibial 
  joint 
  of 
  all 
  pairs 
  of 
  legs 
  fulvous, 
  not 
  dusky. 
  

  

  The 
  ^ 
  head 
  is 
  holoptic 
  and 
  there 
  is 
  no 
  division 
  in 
  the 
  eyes 
  into 
  large 
  and 
  small 
  

   facets 
  ; 
  the 
  eyes 
  are 
  dusky, 
  with 
  a 
  green 
  or 
  bluish-green 
  sheen 
  ; 
  the 
  ? 
  eye 
  also 
  dusky, 
  

   with 
  a 
  slight 
  purplish 
  iridescence, 
  occasionally 
  greenish 
  like 
  that 
  of 
  the 
  (J, 
  but 
  not 
  so 
  

   bright. 
  

  

  