﻿372 
  Mr. 
  C. 
  J. 
  Gahan 
  on 
  mimetic 
  resemblances 
  

  

  The 
  three 
  species 
  form, 
  in 
  fact, 
  a 
  graduated 
  series, 
  

   showing 
  how 
  the 
  process 
  of 
  adaptation 
  has 
  gone 
  on. 
  As 
  

   is 
  the 
  rule 
  in 
  such 
  cases, 
  the 
  mimicked 
  Hispa 
  appears 
  to 
  

   be 
  abundant, 
  whereas 
  the 
  mimicking 
  Lemas 
  are 
  appa- 
  

   rently 
  very 
  rare. 
  

  

  As 
  an 
  additional 
  reason 
  for 
  believing 
  that 
  the 
  species 
  

   of 
  Diabrotica 
  are 
  a 
  protected 
  group, 
  it 
  may 
  be 
  mentioned 
  

   that 
  some 
  of 
  the 
  species 
  belonging 
  to 
  one 
  section 
  in 
  this 
  

   genus 
  are, 
  in 
  colour 
  and 
  marking, 
  extremely 
  like 
  certain 
  

   species 
  of 
  the 
  other 
  section 
  which 
  come 
  from 
  the 
  same 
  

   localities. 
  Now 
  this, 
  according 
  to 
  Mr. 
  Wallace, 
  is 
  a 
  

   phenomenon 
  that 
  does 
  not 
  often 
  occur 
  in 
  unprotected 
  

   groups, 
  though 
  it 
  is 
  frequently 
  to 
  be 
  met 
  with 
  in 
  pro- 
  

   tected 
  genera. 
  

  

  The 
  resemblances 
  between 
  species 
  of 
  Neobrotica 
  and 
  

   certain 
  species 
  of 
  Diabrotica 
  will 
  probably 
  have 
  to 
  be 
  

   placed 
  in 
  the 
  same 
  category 
  as 
  those 
  between 
  species 
  

   belonging 
  to 
  the 
  two 
  different 
  sections 
  of 
  Diabrotica. 
  

  

  Fresh 
  observations 
  upon 
  the 
  species 
  of 
  Lema 
  and 
  

   Diabrotica 
  in 
  their 
  living 
  state 
  will 
  have 
  to 
  be 
  made 
  

   before 
  it 
  can 
  be 
  definitely 
  established 
  that 
  the 
  resem- 
  

   blances 
  between 
  them 
  are 
  cases 
  of 
  true 
  mimicry 
  ; 
  but 
  

   the 
  facts, 
  so 
  far 
  as 
  they 
  are 
  at 
  present 
  known, 
  are, 
  I 
  

   submit, 
  strongly 
  in 
  favour 
  of 
  this 
  conclusion. 
  

  

  List 
  of 
  the 
  Species. 
  

  

  Those 
  that 
  closely 
  resemble 
  each 
  other 
  are 
  bracketed 
  

   together 
  : 
  — 
  

  

  Habitat. 
  

  

  {Lema 
  Batesii, 
  Baly 
  Amazons. 
  

  

  \Diahrotica 
  IQ-guttata, 
  Ol\\ 
  ,, 
  and 
  Cayenne. 
  

  

  [Lema 
  oculata, 
  Lac 
  Ecuador. 
  

  

  [Diabrotica 
  10-guttata, 
  Oliv., 
  var. 
  ... 
  ,, 
  , 
  Upper 
  Amazons. 
  

  

  {Lem,a 
  nigrovittata, 
  Guer 
  Mexico 
  and 
  N. 
  America. 
  

   Diabrotica 
  vittata, 
  Yah 
  ,, 
  ,, 
  

  

  (Lema 
  bisbivittata, 
  Clskrk 
  Mexico. 
  

  

  [Diabrotica 
  Fairmairei, 
  Baly 
  ,, 
  

  

  (Lema 
  vittatipennis, 
  'Baly 
  Amazons. 
  

  

  [Diabrotica 
  separata, 
  Baly 
  ,, 
  

  

  ( 
  Lema 
  BucMeyi, 
  'Balj 
  Ecuador. 
  

  

  [Diabrotica 
  elegans, 
  Baly 
  ,, 
  and 
  Colombia. 
  

  

  (Lema 
  Championi, 
  Jac 
  Panama. 
  

   Diabrotica 
  Qodmani, 
  Jac 
  „ 
  

  

  Neobrotica 
  coeruleo/asciata, 
  Jac. 
  ... 
  „ 
  

  

  