﻿264 
  Ml. 
  E. 
  E. 
  Austen 
  on 
  

  

  species^ 
  tlie 
  members 
  of 
  which 
  res^emble 
  one 
  another 
  so 
  

   closely 
  that 
  extreme 
  care 
  is 
  necessary 
  for 
  their 
  discrimination. 
  

   Lastly, 
  it 
  cannot 
  be 
  too 
  strongly 
  impressed 
  upon 
  all 
  writers 
  

   on 
  Tabanidoe 
  that 
  in 
  a 
  genus 
  like 
  Tabanus 
  (in 
  whicli 
  plastic 
  

   differences 
  between 
  species 
  are 
  seldom 
  obvious, 
  while, 
  on 
  the 
  

   other 
  hand, 
  the 
  number 
  o£ 
  described 
  species 
  already 
  amounts 
  

   to 
  considerably 
  more 
  than 
  nine 
  hundred) 
  descriptions, 
  if 
  they 
  

   are 
  to 
  admit 
  of 
  correct 
  interpretation, 
  must 
  be 
  comparative 
  

   {i. 
  e. 
  must 
  include 
  a 
  reference 
  to 
  allied 
  species, 
  and 
  clearly 
  

   indicate 
  the 
  points 
  in 
  which 
  the 
  supposed 
  new 
  species 
  ditlers 
  

   from 
  them), 
  and 
  sliould 
  always, 
  if 
  possible, 
  be 
  accompanied 
  

   ])y 
  a 
  figure 
  carefully 
  drawn 
  by 
  a 
  competent 
  artist. 
  Photo- 
  

   graphic 
  illustrations 
  are 
  seldom 
  satisfactory, 
  since 
  the 
  

   imperfections 
  of 
  the 
  particular 
  specimen 
  figured, 
  whicli 
  are 
  

   reproduced 
  only 
  too 
  faithfully, 
  frequently 
  obliterate 
  many 
  

   of 
  the 
  specific 
  characters. 
  

  

  The 
  British 
  Museum 
  (Natural 
  History) 
  is 
  much 
  indebted 
  

   to 
  Mr. 
  Taylor 
  for 
  the 
  generous 
  gift 
  of 
  paratypes 
  of 
  all 
  the 
  

   species 
  of 
  Tabanus 
  described 
  by 
  him 
  in 
  his 
  paper 
  as 
  new, 
  as 
  

   well 
  as 
  examples 
  of 
  all 
  but 
  one 
  of 
  those 
  re-described 
  by 
  him 
  

   under 
  previously 
  existing 
  names, 
  and 
  the 
  study 
  of 
  these 
  

   specimens 
  has 
  greatly 
  facilitated 
  the 
  preparation 
  of 
  the 
  sub- 
  

   joined 
  notes. 
  

  

  "Tabanus 
  abslersics. 
  Walker" 
  (p. 
  60, 
  pi. 
  xiv. 
  fig. 
  14) 
  *.— 
  

   Tabanus 
  abstersus, 
  Walk. 
  (Ins. 
  Saund., 
  Dipt. 
  pt. 
  i. 
  p. 
  58, 
  

   1850), 
  = 
  7\ 
  circimidatus, 
  Walk. 
  (List 
  Dipt. 
  Ins. 
  in 
  Coll. 
  Brit. 
  

   Mus., 
  i, 
  p. 
  185, 
  1848). 
  Mr. 
  Taylor's 
  figure, 
  which 
  shows 
  an 
  

   insect 
  in 
  which 
  the 
  majority 
  of 
  the 
  veins 
  in 
  the 
  distal 
  half 
  of 
  

   the 
  wings 
  are 
  strongly 
  infuscated 
  over 
  the 
  greater 
  portion 
  of 
  

   their 
  extent, 
  has 
  nothing 
  to 
  do 
  with 
  Tabanus 
  chxumdatus, 
  

   Walk. 
  (syn. 
  T. 
  abstersus^ 
  Walk.), 
  in 
  which 
  the 
  wings 
  are 
  

   hyaline 
  and 
  the 
  veins 
  are 
  not 
  infuscated, 
  but 
  looks 
  like 
  

   f. 
  Umbatinevris, 
  Macq. 
  (Dipt. 
  Exot., 
  Suppl. 
  iv. 
  p. 
  29 
  (1850), 
  

   nee 
  T. 
  Umbatinevris, 
  Macq., 
  op. 
  cit. 
  Suppl. 
  ii. 
  p. 
  16, 
  184.7). 
  

   The 
  ? 
  specimen 
  forwarded 
  by 
  Mr. 
  Taylor, 
  however, 
  as 
  an 
  

   example 
  of 
  the 
  species 
  regarded 
  by 
  him 
  as 
  Tabanus 
  abstersus, 
  

   Walk., 
  belongs 
  neither 
  to 
  7'. 
  circumdatus, 
  Walk., 
  nor 
  to 
  

   T. 
  Umbatinevris, 
  Macq. 
  (1850), 
  but 
  to 
  a 
  species 
  unknown 
  to 
  

   the 
  present 
  writer. 
  In 
  the 
  specimen 
  sent 
  the 
  angle 
  on 
  the 
  

   upper 
  margin 
  of 
  the 
  expanded 
  portion 
  of 
  the 
  third 
  joint 
  of 
  

   the 
  antennie 
  is 
  produced 
  into 
  a 
  long 
  thumb-like 
  process, 
  

   much 
  as 
  in 
  Rhinoinyza, 
  while 
  the 
  ground-colour 
  of 
  the 
  

   dorsum 
  of 
  the 
  abdomen 
  (with 
  the 
  exception 
  of 
  the 
  lateral 
  

  

  * 
  The 
  details 
  in 
  brackets 
  referto 
  Mr. 
  Taylor'.s 
  paper. 
  

  

  