﻿192 
  Transactions. 
  — 
  Zoology. 
  

  

  Having 
  thus 
  briefly 
  enumerated 
  some 
  of 
  the 
  characters 
  which 
  are 
  

   common 
  to 
  all 
  the 
  Diaspidse, 
  I 
  proceed 
  to 
  particulars. 
  

  

  The 
  group 
  is 
  divisible 
  into 
  several 
  genera, 
  but 
  I 
  need 
  now 
  only 
  mention 
  

   those 
  of 
  which 
  I 
  have 
  obtained 
  specimens 
  in 
  this 
  country. 
  Considering 
  the 
  

   immense 
  number 
  of 
  plants, 
  imported 
  or 
  native^ 
  whether 
  in 
  greenhouses, 
  

   gardens, 
  or 
  the 
  bush, 
  which 
  are 
  attacked 
  by 
  scale 
  insects, 
  and 
  the 
  multi- 
  

   tudinous 
  variations 
  of 
  form 
  and 
  markings 
  which 
  distinguish 
  the 
  indi\'iduals, 
  

   it 
  is 
  likely 
  that 
  future 
  research 
  will 
  discover, 
  if 
  not 
  new 
  families 
  and 
  genera, 
  

   at 
  an}' 
  rate 
  many 
  new 
  species. 
  

  

  The 
  genera 
  known 
  to 
  me 
  at 
  present 
  are 
  the 
  following 
  : 
  — 
  

  

  1. 
  Mytilaspis. 
  This 
  includes 
  the 
  apple 
  scale 
  and 
  many 
  others. 
  The 
  

   shield, 
  or 
  puparium, 
  is 
  elongated 
  ; 
  the 
  two 
  discarded 
  pellicles 
  are 
  seen 
  at 
  

   the 
  smaller 
  end. 
  

  

  2. 
  AspimoTus. 
  Shield 
  of 
  the 
  female 
  round, 
  or 
  nearly 
  so 
  ; 
  that 
  of 
  the 
  

   male 
  somewhat 
  oval 
  ; 
  discarded 
  pellicles 
  in 
  the 
  centre. 
  

  

  8. 
  DiASPis. 
  Shield 
  of 
  the 
  female 
  round, 
  as 
  in 
  the 
  last 
  genus 
  ; 
  the 
  dis- 
  

   carded 
  pellicles 
  usually 
  near 
  the 
  side 
  ; 
  shield 
  af 
  the 
  male 
  elongated. 
  

  

  Subsection 
  I. 
  — 
  Mytilaspis, 
  Linn. 
  

   The 
  females 
  in 
  many 
  species 
  of 
  this 
  genus, 
  as 
  a 
  rule, 
  resemble 
  each 
  

   other 
  in 
  form. 
  The 
  number 
  and 
  disposition 
  of 
  the 
  groups 
  of 
  spinnerets 
  

   offer 
  a 
  means 
  of 
  distinguishing 
  the 
  species. 
  The 
  males, 
  in 
  most 
  cases, 
  are 
  

   unknown. 
  

  

  1. 
  M])tilaspis 
  ijomorum, 
  the 
  apple 
  scale. 
  

  

  Plate 
  v., 
  figs. 
  2a, 
  b, 
  c, 
  d. 
  

  

  This 
  species 
  is 
  not 
  indigenous. 
  The 
  shield, 
  which 
  may 
  be 
  seen 
  cover- 
  

   ing 
  the 
  trunks 
  and 
  branches 
  of 
  our 
  apple, 
  pear, 
  and 
  other 
  trees, 
  is 
  elongated, 
  

   mussel-shaped, 
  brown 
  or 
  grey 
  (I 
  have 
  seen 
  some 
  white). 
  It 
  is 
  open 
  under- 
  

   neath, 
  adhering 
  to 
  the 
  tree 
  with 
  its 
  edges 
  ; 
  it 
  has 
  considerable 
  consistency 
  ; 
  

   length 
  averaging 
  yV 
  inch, 
  breadth 
  nearly 
  -gL- 
  inch. 
  The 
  discarded 
  peUicles 
  

   are 
  at 
  its 
  smaller 
  end, 
  and, 
  when 
  mounted 
  in 
  balsam, 
  the 
  rest 
  of 
  the 
  shield 
  

   is 
  seen 
  to 
  be 
  composed 
  of 
  transverse 
  interlacing 
  curved 
  fibres. 
  

  

  In 
  the 
  spring, 
  a 
  close 
  inspection 
  of 
  a 
  branch 
  of 
  apple 
  tree 
  will 
  show 
  a 
  

   number 
  of 
  extremely 
  minute 
  yellowish 
  specks 
  intermingled 
  with 
  the 
  adult 
  

   puparia. 
  These 
  specks 
  are 
  the 
  young 
  of 
  the 
  insect, 
  hatched 
  and 
  beginning 
  

   to 
  travel 
  on 
  their 
  own 
  account. 
  Plate 
  V., 
  fig, 
  Ic, 
  shows 
  the 
  form 
  at 
  this 
  

   stage. 
  It 
  is 
  oval, 
  flattish, 
  yellow-coloured, 
  with 
  two 
  antennae, 
  each 
  with 
  

   six 
  joints 
  (of 
  which 
  the 
  last 
  is 
  the 
  longest) 
  ; 
  the 
  antenuse 
  have 
  longish 
  hairs 
  

   on 
  each 
  joint. 
  The 
  head 
  is 
  smooth, 
  rather 
  darker 
  in 
  colour 
  than 
  the 
  body, 
  

   with 
  four 
  hairs 
  on 
  its 
  anterior 
  edge. 
  The 
  body 
  is 
  corrugated, 
  each 
  corruga- 
  

   tion 
  having 
  a 
  spine. 
  The 
  anal 
  extremity 
  is 
  yellow, 
  with 
  several 
  hairs, 
  of 
  

   which 
  two 
  are 
  of 
  some 
  length. 
  The 
  legs 
  have 
  short 
  fem.ora, 
  tibi® 
  rather 
  

  

  