﻿Dr. 
  H. 
  Eltringham 
  on 
  the 
  Histology 
  of 
  the 
  Scent-organs. 
  421 
  

  

  are 
  themselves 
  no 
  larger 
  than 
  the 
  brush 
  of 
  a 
  Danaine 
  

   butterfly, 
  yet, 
  as 
  Mr. 
  Mosely 
  has 
  shown, 
  they 
  possess 
  ever- 
  

   sible 
  brushes, 
  scent-scales, 
  expanding 
  membranes 
  and 
  

   tubercles, 
  of 
  a 
  high 
  degree 
  of 
  complication. 
  Moreover, 
  

   the 
  organs 
  in 
  question 
  are 
  not 
  located 
  in 
  the 
  abdominal 
  

   extremity, 
  but 
  in 
  the 
  back 
  of 
  the 
  head. 
  

  

  It 
  is 
  a 
  most 
  interesting 
  case 
  of 
  what 
  may 
  be 
  termed 
  

   the 
  independent 
  development 
  of 
  practically 
  homologous 
  

   structures 
  in 
  insects 
  of 
  different 
  orders, 
  since, 
  however 
  

   nearly 
  related 
  the 
  Lepidoptera 
  and 
  Trichoptera 
  may 
  be, 
  it 
  

   cannot 
  be 
  urged 
  that 
  these 
  scent-organs 
  in 
  the 
  two 
  orders 
  

   had 
  a 
  common 
  ori<iin. 
  

  

  On 
  Descrijitive 
  Terms. 
  

  

  Before 
  describing 
  the 
  organs 
  it 
  may 
  be 
  well 
  to 
  define 
  

   the 
  terms 
  applied 
  to 
  some 
  of 
  the 
  structural 
  details. 
  

  

  It 
  has 
  been 
  suggested 
  to 
  me 
  on 
  more 
  than 
  one 
  occasion 
  

   that 
  the 
  term 
  hair 
  should 
  be 
  confined 
  to 
  mammahan 
  hairs, 
  

   and 
  that 
  insect 
  hairs 
  should 
  be 
  known 
  by 
  some 
  other 
  

   word. 
  I 
  referred 
  to 
  this 
  matter 
  in 
  a 
  note 
  to 
  my 
  paper 
  on 
  

   the 
  Danaine 
  scent-organs 
  {I.e.), 
  and 
  I 
  am 
  still 
  unable 
  to 
  

   see 
  the 
  necessity 
  for 
  any 
  alteration 
  in 
  terms. 
  

  

  The 
  Oxford 
  Dictionary 
  defuies 
  a 
  hair 
  as 
  " 
  One 
  of 
  the 
  

   cylindrical 
  filaments 
  that 
  grow 
  from 
  the 
  skin 
  or 
  integument 
  

   of 
  armnals, 
  especially 
  of 
  most 
  mammals 
  . 
  . 
  . 
  ; 
  applied 
  also 
  

   to 
  similar 
  looking 
  filamentous 
  outgrowths 
  from 
  the 
  bodies 
  

   of 
  insects 
  and 
  other 
  invertebrates, 
  although 
  these 
  are 
  

   generally 
  of 
  different 
  structure." 
  

  

  Similarly, 
  we 
  speak 
  of 
  the 
  seales 
  on 
  the 
  wings 
  of 
  Lepi- 
  

   doptera 
  and 
  on 
  other 
  insects, 
  without 
  in 
  any 
  way 
  implying 
  

   that 
  they 
  are 
  of 
  the 
  same 
  nature 
  as 
  the 
  homonymous 
  

   structures 
  in 
  fish. 
  

  

  There 
  is 
  a 
  greater 
  difl&culty 
  which 
  would 
  not 
  be 
  removed 
  

   by 
  the 
  invention 
  of 
  another 
  word 
  for 
  insect 
  hairs, 
  namely, 
  

   that 
  of 
  deciding 
  the 
  precise 
  point 
  at 
  which 
  an 
  insect 
  hair 
  

   becomes 
  an 
  insect 
  scale. 
  Under 
  a 
  low 
  power 
  a 
  Trichop- 
  

   terous 
  insect 
  such 
  as 
  Hydroptila 
  may 
  be 
  regarded 
  as 
  

   covered 
  with 
  hairs 
  on 
  wings 
  arid 
  body, 
  but 
  on 
  examination 
  

   with 
  a 
  higher 
  magnification 
  it 
  is 
  seen 
  that 
  the 
  structures 
  

   in 
  question 
  would 
  be 
  better 
  described 
  as 
  elongated 
  scales. 
  

   Furthermore, 
  we 
  have 
  in 
  insects 
  certain 
  growths 
  known 
  as 
  

   scent-scales 
  or 
  androconia. 
  It 
  is 
  an 
  unsatisfactory 
  term, 
  

   but 
  as 
  its 
  signification 
  is 
  generally 
  understood 
  we 
  may 
  

  

  