﻿Powell. 
  — 
  On 
  Desis 
  robsoni. 
  267 
  

  

  "I 
  received 
  from 
  Dr. 
  E, 
  v. 
  Martens, 
  of 
  Berlin, 
  a 
  third 
  species 
  of 
  tins 
  

   interesting 
  genus 
  (Desis 
  martensii). 
  It 
  was 
  collected 
  by 
  liiui 
  on 
  coral 
  reefs 
  

   at 
  SingajDore, 
  and 
  kindly 
  given 
  to 
  me 
  for 
  examination. 
  Tins 
  species 
  is 
  

   remarkable 
  in 
  that 
  it 
  has 
  established 
  itself 
  in 
  these 
  reefs 
  which 
  are 
  only 
  

   temporarily 
  uncovered 
  by 
  the 
  sea 
  ; 
  Herr 
  v. 
  Martens 
  has 
  found 
  many 
  speci- 
  

   mens 
  of 
  the 
  spider 
  in 
  this 
  locality. 
  * 
  * 
  * 
  * 
  * 
  * 
  * 
  

   * 
  * 
  That 
  the 
  species 
  discovered 
  by 
  Dr. 
  E. 
  v. 
  Martens 
  and 
  Dr. 
  Johswick,^' 
  

   can 
  really, 
  like 
  our 
  indigenous 
  Argyroneta 
  aquatica, 
  CI., 
  live 
  underwater, 
  

   is 
  to 
  me 
  doubtful 
  in 
  the 
  highest 
  degree, 
  for 
  it 
  is 
  wanting 
  in 
  the 
  outward 
  

   visible 
  signs 
  of 
  the 
  breathing 
  apparatus 
  which 
  corresponds 
  to 
  such 
  sub- 
  

   marine 
  mode 
  of 
  life, 
  and 
  which 
  has 
  been 
  anatomically 
  demonstrated 
  in 
  

   Argyroneta 
  aquatica^. 
  It 
  also 
  speaks 
  against 
  it 
  that 
  yet 
  another 
  species 
  of 
  

   spider, 
  an 
  Atta, 
  was 
  found 
  on 
  the 
  same 
  coral 
  reefs, 
  and 
  we 
  may 
  assume 
  

   with 
  all 
  certainty 
  that 
  this 
  is 
  a 
  true 
  terrestrial 
  form. 
  I 
  opine 
  that 
  these 
  

   spiders, 
  perhaps, 
  in 
  former 
  times, 
  were 
  floated 
  in 
  an 
  accidental 
  manner 
  

   from 
  the 
  land 
  to 
  these 
  reefs, 
  and 
  now 
  live 
  in 
  the 
  holes 
  of 
  the 
  coral 
  bank, 
  

   within 
  which 
  they 
  withdraw 
  at 
  the 
  time 
  of 
  flood, 
  and 
  which 
  they 
  close 
  

   against 
  the 
  entrance 
  of 
  the 
  water 
  with 
  a 
  thick 
  web. 
  * 
  * 
  When 
  once 
  

   both 
  sexes 
  had 
  been 
  transferred 
  to 
  the 
  coral 
  reefs, 
  Desis 
  martensii 
  would 
  

   increase 
  and 
  form 
  a 
  colony 
  there." 
  

  

  I 
  take 
  the 
  liberty 
  of 
  quoting 
  a 
  further 
  valuable 
  communication 
  from 
  

   Dr. 
  E. 
  V. 
  Martens 
  on 
  the 
  discovery 
  of 
  this 
  interesting 
  spider, 
  as 
  follows 
  : 
  — 
  

  

  "During 
  my 
  residence 
  at 
  Singapore, 
  in 
  October, 
  1861, 
  I 
  repeatedly 
  

   visited 
  a 
  coral 
  bank 
  in 
  the 
  neighbourhood 
  of 
  New 
  Harbour, 
  of 
  which 
  large 
  

   tracts 
  were 
  exposed 
  above 
  water 
  during 
  the 
  ebb, 
  at 
  the 
  times 
  of 
  new 
  and 
  full 
  

   moon. 
  My 
  attention 
  was 
  chiefly 
  directed 
  to 
  Crustacea 
  and 
  Mollusca; 
  I 
  tore 
  

   off 
  pieces 
  of 
  coral 
  and 
  broke 
  them 
  up 
  to 
  get 
  at 
  the 
  creatures 
  hidden 
  within. 
  

   To 
  my 
  astonishment 
  I 
  several 
  times 
  observed 
  spiders 
  hurriedly 
  escaping, 
  

   the 
  idea 
  occurred 
  to 
  me 
  at 
  first 
  that 
  we 
  ourselves 
  had 
  brought 
  them 
  from 
  

   the 
  shore 
  in 
  our 
  clothing. 
  I 
  generally 
  went 
  with 
  the 
  late 
  staff-surgeon, 
  Dr. 
  

   Johswick, 
  in 
  a 
  little 
  skiff 
  pulled 
  by 
  a 
  Chinese 
  from 
  the 
  frigate 
  ' 
  Thetis 
  ' 
  

   which 
  lay 
  in 
  the 
  roadstead, 
  or 
  from 
  the 
  town, 
  distant 
  about 
  half-a-league 
  

   from 
  the 
  coral 
  reef. 
  This 
  suspicion 
  was 
  rendered 
  unlikely 
  by 
  the 
  frequent 
  

   repetition 
  of 
  the 
  event, 
  and 
  conclusively 
  disproved, 
  as 
  Dr. 
  Johswick 
  found 
  a 
  

   web 
  of 
  undoubtedly 
  one 
  of 
  these 
  spiders 
  in 
  an 
  old 
  dead 
  mussel 
  shell, 
  between 
  

   the 
  coral, 
  stretched 
  sheet-like 
  in 
  the 
  cavity 
  of 
  the 
  shell. 
  "| 
  

  

  * 
  Sitzungsbericlit 
  der 
  Gesellschaft 
  Naturforscheuder 
  Frennde 
  zu 
  Berlin 
  vom 
  Mai 
  24, 
  

   1864, 
  p. 
  10. 
  

  

  t 
  Grube 
  " 
  Einige 
  Eesultate 
  aus 
  Untersucliungen 
  iiber 
  die 
  Anatomie 
  der 
  Spinnen," 
  

   in 
  Miiller's 
  " 
  Archiv. 
  fiir 
  Anat. 
  und 
  Physiol 
  ogie," 
  1842, 
  p. 
  300 
  ; 
  und 
  Menge 
  " 
  Ueber 
  die 
  

   Lebensweise 
  der 
  Arachniden," 
  " 
  Neueste 
  Schriiten 
  der 
  Naturhistorischeu 
  Gesellschaft,'' 
  

   in 
  Danzig, 
  IV. 
  Band 
  Hit. 
  i, 
  p. 
  23. 
  

  

  + 
  Koch, 
  Arach. 
  Austr., 
  pp. 
  349, 
  350, 
  

  

  