﻿Segments 
  and 
  Aedeagus 
  of 
  Habrocerus 
  capillaricornis. 
  401 
  

  

  portion 
  of 
  the 
  Coleoptera), 
  it 
  is 
  the 
  chief 
  functional 
  organ, 
  

   the 
  tegmen 
  and 
  median 
  lobe 
  serving 
  for 
  its 
  protection, 
  

   guidance 
  and 
  protrusion. 
  

  

  In 
  Leistotrophus 
  the 
  basal 
  portion 
  of 
  the 
  median 
  lobe 
  

   forms 
  but 
  a 
  small 
  bulb, 
  and 
  the 
  distal 
  portion 
  is 
  compara- 
  

   tively 
  large; 
  in 
  Tachyporus 
  the 
  bulb 
  is 
  much 
  larger 
  and 
  

   the 
  distal 
  portion 
  smaller. 
  The 
  connection 
  with 
  the 
  inner 
  

   surface 
  of 
  the 
  ninth 
  segment 
  is 
  by 
  a 
  membrane 
  arising 
  

   around 
  the 
  edge 
  of 
  the 
  median 
  foramen; 
  the 
  anus 
  opens 
  

   on 
  the 
  dorsal 
  portion 
  of 
  this 
  membrane 
  (fig. 
  3, 
  im 
  1 
  ; 
  in 
  

   this 
  figure 
  the 
  aedeagus 
  is 
  shown 
  drawn 
  out 
  of 
  this 
  

   membrane 
  in 
  a 
  diagrammatic 
  manner 
  impossible 
  to 
  do 
  

   in 
  nature). 
  

  

  In 
  Habrocerus 
  capillaricornis 
  there 
  is 
  nothing 
  to 
  corre- 
  

   spond 
  to 
  the 
  highly 
  developed 
  median 
  lobe 
  of 
  Leistotrophus 
  

   and 
  Tachyporus, 
  bvit 
  the 
  internal 
  sac 
  is 
  well 
  developed 
  and 
  

   specialised 
  (is). 
  In 
  the 
  place 
  of 
  the 
  median 
  lobe 
  we 
  find 
  

   a 
  membranous 
  tube 
  opening 
  in 
  the 
  dorsal 
  aspect 
  of 
  the 
  

   small 
  trilobe 
  process 
  (figs. 
  10 
  and 
  11, 
  /), 
  on 
  the 
  same 
  

   membrane 
  as 
  the 
  anus 
  is 
  situated. 
  This 
  tube 
  enlarges 
  

   coneshape 
  and 
  is 
  inflexed 
  {h) 
  for 
  a 
  short 
  distance 
  and 
  then 
  

   reflexed 
  (i), 
  this 
  reflexion 
  continuing 
  as 
  the 
  internal 
  sac; 
  

   the 
  inflexed 
  membrane 
  {tg) 
  is 
  in 
  close 
  contact 
  with 
  the 
  outer 
  

   membrane 
  [im 
  1), 
  and 
  there 
  is 
  a 
  small, 
  semichitinised, 
  

   triangular 
  plate 
  (e) 
  at 
  the 
  point 
  of 
  inflexion. 
  The 
  outer 
  

   membrane 
  {m 
  1) 
  is 
  homologous 
  in 
  position 
  to 
  the 
  connecting 
  

   membrane 
  {im 
  1) 
  of 
  Tachyporus 
  and 
  Leistotfophus 
  and 
  the 
  

   inner, 
  inflexed 
  membrane 
  {tg) 
  with 
  the 
  aedeagus. 
  

  

  The 
  internal 
  sac 
  (fig. 
  12, 
  is) 
  is 
  large 
  and 
  covered 
  with 
  

   small 
  spines 
  pointing 
  basad 
  ; 
  along 
  one 
  side 
  there 
  is 
  a 
  row 
  

   of 
  nine 
  spines 
  fixed 
  to 
  the 
  sac 
  by 
  large 
  bases 
  ; 
  the 
  apical 
  

   three 
  are 
  smaller 
  than 
  the 
  others 
  ; 
  along 
  the 
  opposite 
  

   aspect 
  there 
  is 
  a 
  row 
  of 
  small 
  semitriangular 
  plates, 
  one 
  

   overlapping 
  the 
  other. 
  

  

  The 
  membranous 
  cone 
  (fig. 
  10, 
  im 
  1, 
  tg) 
  varies 
  somewhat 
  

   in 
  size 
  in 
  different 
  specimens, 
  the 
  one 
  figured 
  is 
  very 
  distinct, 
  

   but 
  others 
  are 
  smaller 
  and 
  not 
  so 
  plain. 
  In 
  the 
  absence 
  of 
  

   fresh 
  or 
  spirit 
  specimens 
  certain 
  important 
  points 
  relating 
  

   to 
  the 
  musculature 
  have 
  to 
  be 
  left 
  unexplained, 
  but 
  there 
  

   is 
  a 
  large 
  group 
  of 
  muscles 
  attached 
  to 
  the 
  margin 
  of 
  the 
  

   cone 
  (fig. 
  10, 
  h) 
  enveloping 
  the 
  internal 
  sac. 
  This 
  evidently 
  

   acts 
  as 
  a 
  muscular 
  bulb 
  in 
  a 
  somewhat 
  similar 
  manner 
  to 
  

   the 
  muscular 
  bulb 
  in 
  certain 
  Lamellicornia 
  (i.e. 
  Melolontha 
  

   vulgaris). 
  There 
  are 
  several 
  points 
  in 
  the 
  structure 
  of 
  the 
  

  

  TRANS. 
  ENT. 
  SOC. 
  LOND. 
  1919. 
  — 
  PARTS 
  III, 
  IV. 
  (DEC.) 
  D 
  I> 
  

  

  