﻿204 
  Transactions. 
  — 
  Zoology, 
  

  

  The 
  Lecanidfe 
  affect 
  the 
  most 
  varied 
  forms 
  and 
  habits. 
  Some 
  are 
  flat, 
  

   some 
  are 
  globular 
  ; 
  some 
  are 
  naked, 
  some 
  covered 
  with 
  a 
  test 
  which 
  may 
  be 
  

   cottony, 
  or 
  glassy, 
  or 
  waxy 
  ; 
  some 
  are 
  viviparous, 
  some 
  form 
  cocoons 
  or 
  

   nests 
  for 
  their 
  eggs. 
  But 
  there 
  are 
  two 
  characters 
  which 
  very 
  clearly 
  

   distinguish 
  them 
  all 
  from 
  the 
  Diaspid^. 
  These 
  are 
  the 
  presence 
  of 
  a 
  

   mentum 
  or 
  under 
  lip, 
  and 
  an 
  abdomen 
  cleft 
  at 
  its 
  posterior 
  extremity, 
  with 
  

   two 
  triangular 
  lobes 
  above 
  the 
  cleft. 
  

  

  In 
  the 
  Diaspidas 
  the 
  rostral 
  sets 
  are 
  clear 
  of 
  the 
  body 
  from 
  the 
  moment 
  

   they 
  leave 
  the 
  tip 
  of 
  the 
  rostrum. 
  In 
  the 
  Lecanidas 
  the 
  setae 
  pass 
  some 
  

   little 
  way 
  down 
  the 
  body, 
  and 
  then, 
  returning 
  towards 
  the 
  rostrum, 
  pass 
  

   through 
  a 
  second 
  tube, 
  or 
  mentum, 
  as 
  shown 
  in 
  plate 
  VI., 
  fig. 
  11a. 
  This 
  

   mentum 
  is 
  also 
  visible 
  in 
  the 
  next 
  group, 
  the 
  Coccids 
  proper; 
  but 
  it 
  is 
  there 
  

   articulate, 
  whereas 
  in 
  the 
  Lecanidae 
  it 
  has 
  but 
  one 
  segment. 
  

  

  The 
  rostral 
  setse 
  appear 
  to 
  be 
  generally 
  three, 
  but 
  in 
  some 
  instances 
  I 
  

   can 
  observe 
  that 
  one 
  of 
  them 
  is 
  double. 
  

  

  The 
  abdominal 
  cleft 
  and 
  its 
  lobes 
  are 
  shown 
  in 
  plate 
  VI., 
  fig. 
  lib. 
  There 
  

   are 
  of 
  coarse 
  specific 
  differences 
  in 
  the 
  size 
  and 
  shape 
  of 
  these 
  lobes, 
  in 
  the 
  

   hairs 
  on 
  the 
  abdomen, 
  and 
  in 
  the 
  spines 
  surrounding 
  the 
  anal 
  ring. 
  

  

  In 
  plate 
  VI., 
  fig. 
  lie, 
  I 
  give 
  a 
  representation 
  of 
  the 
  respiratory 
  system 
  of 
  

   a 
  Lecanium, 
  the 
  arrangement 
  of 
  which 
  does 
  not 
  greatly 
  differ 
  in 
  the 
  species 
  

   which 
  I 
  have 
  observed. 
  It 
  will 
  be 
  seen 
  that 
  there 
  are 
  four 
  stigmata, 
  from 
  

   each 
  of 
  which 
  start 
  large 
  trachea) 
  covering 
  the 
  body 
  with 
  their 
  ramifica- 
  

   tions. 
  Fig. 
  lid 
  gives 
  a 
  magnified 
  figure 
  of 
  a 
  stigma, 
  mounted 
  in 
  balsam, 
  

   with 
  the 
  stigmatic 
  spines. 
  

  

  The 
  antennae 
  in 
  the 
  young 
  insect 
  have 
  usually 
  six 
  or 
  seven 
  joints 
  ; 
  in 
  

   the 
  adult 
  feraale 
  seven 
  or 
  eight. 
  The 
  feet 
  end 
  in 
  a 
  single 
  claw 
  ; 
  just 
  above 
  

   the 
  chuv 
  spring 
  four 
  hairs, 
  of 
  which 
  the 
  two 
  uppermost 
  are 
  long, 
  ending 
  in 
  

   a 
  small 
  knob, 
  the 
  lower 
  pair 
  generally 
  shorter 
  and 
  broader, 
  swelling 
  out 
  into 
  

   a 
  club 
  at 
  the 
  end. 
  See 
  plate 
  VI., 
  fig. 
  lie. 
  

  

  The 
  males 
  of 
  most 
  of 
  the 
  Lecanidae 
  are, 
  I 
  beheve, 
  unknown. 
  I 
  have 
  

   been 
  fortunate 
  enough 
  to 
  procure 
  specimens 
  of 
  males 
  of 
  one 
  indigenous 
  

   species. 
  

  

  The 
  two 
  distinguishing 
  characters 
  just 
  mentioned, 
  the 
  uni-articulate 
  

   mentum 
  and 
  the 
  bi-lobed 
  abdomen, 
  are 
  best 
  observed 
  in 
  the 
  young 
  insect. 
  

   The 
  former, 
  indeed, 
  is 
  often 
  not 
  to 
  be 
  made 
  out 
  in 
  the 
  adult, 
  but 
  the 
  latter 
  

   is 
  generally 
  conspicuous 
  enough 
  to 
  prevent 
  mistaking 
  one 
  of 
  the 
  Lecanids 
  

   for 
  an 
  insect 
  belonging 
  to 
  another 
  group. 
  

  

  All 
  the 
  LecanidiB 
  are 
  very 
  much 
  infested 
  by 
  a 
  fungus, 
  apparently 
  of 
  the 
  

   order 
  Coniomycetes. 
  No 
  doubt 
  most 
  iseople 
  have 
  observed 
  that 
  plants 
  

   attacked 
  by 
  scale, 
  such 
  as 
  for 
  instance 
  the 
  holly, 
  or 
  the 
  ivy, 
  have 
  also 
  their 
  

   leaves 
  much 
  blackened. 
  The 
  blackening 
  is 
  due 
  to 
  the 
  fungus 
  just 
  men- 
  

   tioned. 
  

  

  