﻿158 
  BRUCE 
  F. 
  CUMMINGS. 
  

  

  Tracheal 
  System 
  (fig. 
  2). 
  — 
  The 
  systematic 
  value 
  of 
  the 
  tracheal 
  system 
  will 
  only 
  

   emerge 
  after 
  more 
  prolonged 
  study. 
  Not 
  much 
  is 
  known 
  at 
  present 
  about 
  it, 
  but 
  in 
  

   view 
  of 
  such 
  information 
  as 
  we 
  already 
  have 
  at 
  our 
  disposal, 
  it 
  is 
  tempting 
  

   to 
  hazard 
  the 
  opinion 
  that 
  well 
  marked 
  generic, 
  if 
  not 
  specific, 
  characters 
  

   will 
  be 
  found, 
  and 
  that 
  in 
  the 
  ultimate 
  classification 
  of 
  these 
  insects 
  this 
  important 
  

   system, 
  together 
  with 
  the 
  others, 
  will 
  be 
  drawn 
  upon 
  to 
  give 
  at 
  least 
  its 
  tittle 
  of 
  

   evidence 
  in 
  the 
  difficult 
  questions 
  of 
  phylogenetic 
  affinity. 
  

  

  In 
  H. 
  taurotragi 
  the 
  system 
  consists 
  of 
  two 
  cardinal 
  trunks 
  situated 
  longitudinally 
  

   one 
  on 
  each 
  side, 
  and 
  connected 
  by 
  a 
  commissure 
  at 
  the 
  posterior 
  end 
  of 
  the 
  abdomen. 
  

   Each 
  cardinal 
  trunk 
  gives 
  off 
  (in 
  the 
  abdomen) 
  6 
  lateral 
  diverticula 
  running 
  out 
  to 
  

   the 
  spiracles. 
  In 
  the 
  thorax 
  there 
  is 
  one 
  large 
  lateral 
  diverticulum 
  which 
  runs 
  up 
  

   dorsally 
  to 
  the 
  single 
  mesothoracic 
  spiracle. 
  This 
  diverticulum 
  exceeds 
  the 
  main 
  

   trunk 
  itself 
  in 
  girth. 
  There 
  is 
  an 
  enormous 
  visceral 
  complex 
  formed 
  by 
  the 
  rami- 
  

   fying 
  branches 
  of 
  roots 
  arising 
  from 
  the 
  cardinal 
  trunks. 
  Another 
  large 
  complex 
  

   exists 
  in 
  the 
  head, 
  formed 
  by 
  the 
  cephalic 
  branches. 
  In 
  the 
  male 
  the 
  commissure 
  

   runs 
  across 
  the 
  posterior 
  end 
  of 
  the 
  abdomen, 
  dorsal 
  to 
  the 
  genitalia, 
  just 
  below 
  the 
  

   level 
  where 
  the 
  parameres 
  articulate 
  with 
  the 
  basal 
  plate. 
  In 
  the 
  female 
  the 
  com- 
  

   missure 
  runs 
  across 
  the 
  genital 
  plate. 
  With 
  the 
  exception 
  of 
  the 
  last, 
  each 
  lateral 
  

   diverticulum 
  of 
  the 
  cardinal 
  trunk 
  gives 
  off 
  two 
  branches, 
  one 
  anterior 
  and 
  the 
  

   other 
  posterior, 
  the 
  latter 
  being 
  the 
  larger. 
  Other 
  roots 
  arising 
  from 
  the 
  cardinal 
  

   trunks 
  in 
  the 
  abdomen 
  are 
  shown 
  in 
  fig. 
  2. 
  As 
  regards 
  the 
  origin 
  of 
  the 
  smaller 
  roots, 
  

   the 
  tracheal 
  system 
  does 
  not 
  show 
  a 
  symmetrical 
  arrangement 
  on 
  each 
  side. 
  

  

  In 
  the 
  thorax 
  we 
  find 
  a 
  large 
  trunk 
  given 
  off 
  to 
  the 
  third 
  pair 
  of 
  legs, 
  which 
  divides 
  

   into 
  two 
  and 
  then 
  into 
  still 
  smaller 
  divisions. 
  Two 
  branches 
  likewise 
  supply 
  the 
  

   second 
  pair 
  of 
  legs, 
  but 
  each 
  of 
  these 
  arises 
  separately. 
  Just 
  in 
  front 
  of 
  these 
  the 
  

   large 
  trunk 
  to 
  the 
  mesothoracic 
  spiracle 
  is 
  given 
  off. 
  A 
  commissure 
  accompanies 
  

   the 
  cardinal 
  trunk 
  along 
  its 
  inner 
  side 
  from 
  the 
  base 
  of 
  the 
  branch 
  to 
  the 
  third 
  pair 
  

   of 
  legs, 
  anastomosing 
  again 
  with 
  the 
  main 
  trunk 
  in 
  front, 
  just 
  at 
  the 
  point 
  where 
  the 
  

   trunk 
  gives 
  off 
  the 
  branch 
  to 
  the 
  mesothoracic 
  spiracle. 
  This 
  commissure 
  gives 
  

   origin 
  to 
  no 
  smaller 
  branches. 
  Each 
  cardinal 
  trunk 
  terminates 
  in 
  the 
  prothorax 
  by 
  

   trifurcating 
  into 
  three 
  relatively 
  small 
  branches, 
  two 
  of 
  which 
  go 
  to 
  the 
  first 
  pair 
  of 
  

   legs 
  and 
  one 
  to 
  the 
  head. 
  Their 
  method 
  of 
  origin 
  is 
  displayed 
  in 
  fig. 
  2. 
  

  

  The 
  spiracles 
  present 
  some 
  features 
  of 
  interest. 
  Mjoberg 
  (6, 
  p. 
  217) 
  has 
  figured 
  

   and 
  described 
  the 
  spiracles 
  and 
  closing 
  apparatus 
  in 
  several 
  different 
  species 
  of 
  

   Anoplura. 
  From 
  these 
  figures, 
  it 
  will 
  be 
  seen 
  that 
  the 
  various 
  species 
  differ 
  some- 
  

   times 
  very 
  considerably 
  in 
  regard 
  to 
  these 
  characters. 
  In 
  all 
  of 
  them, 
  and 
  in 
  

   H 
  .tuberculatus 
  as 
  well, 
  the 
  spiracular 
  chamber 
  shows 
  the 
  same 
  essential 
  features, 
  i.e., 
  a 
  

   narrow 
  neck 
  and 
  a 
  single 
  chitinous 
  "tab" 
  standing 
  off 
  from 
  the 
  neck 
  and 
  giving 
  

   attachment 
  to 
  the 
  muscle 
  of 
  the 
  closing 
  apparatus. 
  But 
  in 
  H. 
  taurotragi 
  these 
  

   " 
  tabs 
  " 
  are 
  two 
  in 
  number, 
  one 
  on 
  each 
  side 
  of 
  the 
  neck. 
  Each 
  abdominal 
  spiracle 
  

   opens 
  at 
  the 
  extreme 
  lateral 
  margin 
  of 
  each 
  segment. 
  The 
  somewhat 
  concave 
  pleural 
  

   plate 
  lies 
  on 
  the 
  ventral 
  surface 
  of 
  the 
  pleural 
  area 
  and 
  the 
  spiracular 
  chamber 
  lies 
  

   in 
  this 
  concavity 
  and 
  can 
  be 
  seen 
  from 
  above 
  through 
  the 
  transparent 
  dorsal 
  

   integument. 
  

  

  Male 
  Copulatory 
  Apparatus. 
  — 
  This 
  agrees 
  closely 
  with 
  the 
  figure 
  given 
  by 
  Mjoberg 
  

   (6, 
  p. 
  231) 
  for 
  Haematopinus 
  phtiriopsis. 
  That 
  is 
  to 
  say, 
  the 
  parameres 
  are 
  united 
  

  

  