﻿boycott: 
  sexual 
  CHAKACTEKS 
  ix 
  fomatias 
  elegaxs. 
  131 
  

  

  Number 
  of 
  Rows. 
  

  

  These 
  figures 
  sliow 
  that 
  the 
  females 
  have 
  a 
  largei* 
  radula 
  than 
  the 
  

   males 
  hut 
  about 
  the 
  same 
  number 
  of 
  transverse 
  rows 
  ; 
  in 
  the 
  males 
  the 
  

   number 
  of 
  rows 
  appears 
  to 
  increase 
  as 
  the 
  shell 
  becomes 
  larger, 
  while 
  

   in 
  the 
  females 
  it 
  remains 
  tlie 
  same 
  or 
  even 
  becomes 
  less. 
  Whether 
  

   the 
  difference 
  in 
  length 
  is 
  due 
  to 
  the 
  larger 
  size 
  of 
  tlie 
  females 
  is 
  

   uncertain 
  without 
  more 
  ample 
  data 
  for 
  males 
  and 
  females 
  of 
  equal 
  

   size.* 
  Relatively 
  to 
  the 
  volume 
  of 
  the 
  shell 
  and 
  tlie 
  weight 
  of 
  the 
  

   body 
  the 
  female 
  radula 
  is 
  obviously 
  short 
  and 
  has 
  few 
  rows, 
  but 
  the 
  

   same 
  is 
  true 
  of 
  the 
  larger 
  males 
  and 
  females 
  compared 
  with 
  smaller 
  

   individuals 
  of 
  the 
  same 
  sex. 
  The 
  ratio 
  of 
  the 
  volume 
  of 
  the 
  female 
  

   shell 
  to 
  that 
  of 
  the 
  male 
  is 
  about 
  130 
  : 
  lOO.''* 
  The 
  average 
  weights 
  of 
  

   a 
  series 
  of 
  bodies 
  dried 
  at 
  100° 
  C. 
  are 
  given 
  below, 
  the 
  general 
  ratio 
  

   being 
  138 
  : 
  100. 
  On 
  tlie 
  whole, 
  therefore, 
  while 
  the 
  radula 
  of 
  the 
  

   females 
  is 
  slightly 
  hut 
  clearly 
  different 
  from 
  that 
  of 
  the 
  males, 
  it 
  is 
  

   hardly 
  legitimate 
  to 
  call 
  it 
  a 
  sexual 
  difference 
  without 
  clearer 
  

   exclusion 
  of 
  the 
  size 
  factor. 
  

  

  V, 
  Sex 
  of 
  Immature 
  Specimens. 
  

  

  Those 
  of 
  the 
  immature 
  specimens 
  -which 
  -were 
  10 
  mm, 
  or 
  more 
  in 
  

   altitude 
  were 
  examined 
  for 
  sex 
  and 
  gave 
  40 
  per 
  cent 
  males,^ 
  dis- 
  

   tributed 
  as 
  follows 
  : 
  — 
  

  

  ' 
  It 
  is 
  obviously 
  illegitimate 
  to 
  bring 
  immature 
  specimens 
  into 
  the 
  comparison, 
  

   the 
  radula 
  being 
  a 
  feeding 
  organ, 
  and 
  the 
  amount 
  of 
  food 
  required 
  being 
  

   presumably 
  quite 
  different 
  in 
  growing 
  and 
  adult 
  individuals. 
  

  

  ^ 
  i.e. 
  assuming 
  the 
  shell 
  is 
  a 
  regular 
  cone 
  with 
  a 
  base 
  equal 
  to 
  the 
  measured 
  

   diameter 
  and 
  a 
  height 
  equal 
  to 
  the 
  measured 
  altitude. 
  

  

  ^ 
  This 
  does 
  not 
  satisfy 
  the 
  statistical 
  test 
  that 
  there 
  are 
  really 
  fewer 
  males 
  in 
  

   the 
  immature 
  than 
  in 
  the 
  mature 
  specimens 
  (58 
  per 
  cent). 
  

  

  