﻿216 
  

  

  STANLEY 
  HIRST. 
  — 
  ON 
  THE 
  PARASITIC 
  ACARI 
  

  

  Family 
  Gamasidae. 
  

   I. 
  Dermanyssus 
  muris, 
  Hirst 
  (figs. 
  1-4). 
  

  

  Dermanyssus 
  (Liponyssoides) 
  muris, 
  Hirst, 
  Bull. 
  Ent. 
  Kes. 
  iv, 
  pp. 
  120-122, 
  text-figs. 
  

   1 
  and 
  2 
  (1913). 
  

  

  $. 
  Dorsal 
  shield 
  and 
  anal 
  plate 
  shaped 
  very 
  like 
  those 
  of 
  D. 
  gallinae, 
  Eedi, 
  but 
  

   the 
  shield 
  has 
  long 
  hairs 
  on 
  its 
  surface 
  instead 
  of 
  short 
  ones. 
  Sternal 
  plate 
  trapezoidal 
  

   in 
  shape 
  and 
  furnished 
  with 
  three 
  pairs 
  of 
  long 
  fine 
  hairs. 
  Genito-ventral 
  plate 
  much 
  

   narrower, 
  especially 
  posteriorly, 
  than 
  is 
  the 
  case 
  in 
  D. 
  gallinae 
  ; 
  on 
  either 
  side 
  of 
  and 
  

   parallel 
  with 
  this 
  plate, 
  there 
  are 
  two 
  very 
  narrow 
  (linear) 
  platelets, 
  which 
  are 
  not 
  

   very 
  easy 
  to 
  see. 
  A 
  pair 
  of 
  little 
  oval 
  platelets 
  are 
  also 
  present 
  behind 
  each 
  of 
  the 
  

   fourth 
  coxae. 
  Peritreme 
  long, 
  seemingly 
  extending 
  as 
  far 
  forwards 
  as 
  or 
  slightly 
  

   beyond 
  the 
  coxa 
  of 
  the 
  second 
  leg. 
  Anterior 
  surface 
  of 
  coxa 
  of 
  second 
  leg 
  armed 
  

   dorsally 
  with 
  a 
  sharp 
  forwardly 
  directed 
  spur. 
  Length 
  of 
  body 
  (gorged 
  specimen), 
  

   1-87 
  mm. 
  

  

  Fig. 
  2. 
  Dermanyssus 
  muris, 
  Hirst, 
  $ 
  ; 
  ventral 
  and 
  dorsal 
  aspects. 
  

  

  cJ. 
  Dorsal 
  shield 
  long 
  and 
  fairly 
  wide, 
  the 
  posterior 
  end 
  being 
  rounded 
  (occasionally 
  

   somewhat 
  angular) 
  instead 
  of 
  subtruncate 
  as 
  in 
  the 
  female 
  ; 
  at 
  some 
  distance 
  from 
  

   the 
  anterior 
  end 
  of 
  this 
  shield, 
  there 
  is 
  a 
  pair 
  of 
  rather 
  large 
  eye-like 
  organs 
  on 
  its 
  

   surface 
  and 
  they 
  are 
  widely 
  separated 
  from 
  one 
  another, 
  being 
  placed 
  close 
  to 
  the 
  

  

  