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  STANLEY 
  HIRST. 
  — 
  PRELIMINARY 
  LIST 
  OF 
  THE 
  

  

  (for 
  the 
  shape 
  and 
  exact 
  position 
  of 
  these 
  shields, 
  see 
  fig. 
  1). 
  The 
  two 
  large 
  shields 
  

   are 
  marked 
  with 
  a 
  reticulate 
  sculpturing 
  formed 
  by 
  numerous 
  fine 
  lines. 
  Sternal 
  

   plate 
  reaching 
  as 
  far 
  back 
  as 
  the 
  interval 
  between 
  the 
  third 
  and 
  fourth 
  coxae, 
  

   its 
  posterior 
  end 
  being 
  rather 
  abruptly 
  narrowed 
  ; 
  three 
  pairs 
  of 
  long 
  fine 
  hairs 
  are 
  

   present 
  on 
  this 
  plate. 
  Peritreme 
  short, 
  anteriorly 
  it 
  does 
  not 
  pass 
  the 
  third 
  coxa. 
  

   Length 
  of 
  body, 
  *65 
  mm. 
  

  

  Deutonymph 
  (fig. 
  2). 
  Dorsal 
  surface 
  covered 
  with 
  a 
  single 
  undivided 
  shield 
  which 
  

  

  Fig. 
  2. 
  Laelaps 
  echidninus, 
  Berl., 
  

   ventral 
  view 
  of 
  deutonymph. 
  

  

  is 
  marked 
  by 
  numerous 
  fine 
  lines, 
  mostly 
  running 
  transversely 
  across 
  its 
  surface. 
  

   Sternal 
  plate 
  narrower 
  and 
  much 
  longer 
  than 
  that 
  of 
  the 
  protonyinph, 
  being 
  prolonged 
  

   posteriorly 
  well 
  beyond 
  the 
  fourth 
  coxae 
  ; 
  there 
  are 
  four 
  pairs 
  of 
  long 
  fine 
  hairs 
  on 
  

   its 
  surface. 
  Peritreme 
  extending 
  almost 
  as 
  far 
  forwards 
  as 
  the 
  middle 
  of 
  the 
  first 
  

   coxa. 
  Length 
  of 
  body, 
  *8 
  mm. 
  

  

  (J. 
  Chelicera 
  fairly 
  long 
  and 
  styliform 
  ; 
  at 
  its 
  base 
  there 
  is 
  a 
  delicate 
  little 
  lancet- 
  

   shaped 
  structure, 
  and 
  a 
  membranous 
  lobe, 
  which 
  perhaps 
  functions 
  as 
  a 
  sucker, 
  is 
  

   also 
  present 
  on 
  the 
  inner 
  ventral 
  surface 
  of 
  the 
  basal 
  end 
  (fig. 
  3). 
  

  

  Fig. 
  3. 
  Laelaps 
  ecnidninus, 
  Berl. 
  ; 
  chelicera 
  of 
  male. 
  

  

  Loc. 
  Several 
  localities 
  for 
  this 
  species 
  are 
  given 
  in 
  my 
  paper 
  quoted 
  above. 
  During 
  

   July 
  and 
  August 
  1913, 
  1 
  found 
  eleven 
  more 
  specimens 
  on 
  about 
  three 
  dozen 
  wild 
  rats 
  

   (Mus 
  norvegicus) 
  captured 
  at 
  different 
  times 
  near 
  Watford, 
  Hertfordshire. 
  The 
  

   nymphs 
  and 
  male 
  described 
  above 
  were 
  bred 
  (on 
  white 
  rats) 
  from 
  these 
  specimens. 
  

  

  