﻿130 
  

  

  PROCEEDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIETY. 
  

  

  III. 
  Weight 
  of 
  Shelf,. 
  

   The 
  average 
  weights 
  of 
  the 
  shells 
  with 
  opercula 
  (dried 
  at 
  100° 
  C.) 
  

   showed 
  no 
  difference 
  between 
  males 
  and 
  females 
  except 
  that 
  due 
  to 
  

   size.^ 
  In 
  the 
  13'5 
  mm. 
  group 
  the 
  sizes 
  and 
  weights 
  are 
  identical: 
  in 
  

   the 
  14"0 
  mm. 
  group 
  the 
  females 
  (14'2x 
  lO'l) 
  had 
  larger 
  shells 
  than 
  

   the 
  males 
  (14'0x9-9). 
  Hence 
  we 
  may 
  conclude 
  that 
  there 
  is 
  no 
  

   sexual 
  difference 
  in 
  shell 
  thickness. 
  

  

  Group. 
  

  

  mm. 
  alt. 
  

   12-5-12-9 
  

   1.3 
  0-13 
  -4 
  

   130-13-9 
  

   140-14-4 
  

   140-14-9 
  

   150-15-4 
  

  

  Total 
  

  

  Average 
  Weight 
  in 
  Milligrammes. 
  

  

  Males. 
  Females. 
  

  

  154 
  — 
  

  

  169 
  — 
  

  

  186 
  186 
  

  

  198 
  205 
  

  

  230 
  

  

  244 
  

  

  213 
  

  

  171 
  

  

  IV. 
  IIadola. 
  

   The 
  bodies 
  were 
  used 
  for 
  various 
  purposes 
  ; 
  from 
  185 
  (112 
  males, 
  

   73 
  females) 
  the 
  radulte 
  were 
  extracted 
  by 
  boiling 
  with 
  caustic 
  soda 
  

   and 
  mounted 
  in 
  Farrant's 
  solution. 
  No 
  sexual 
  difference 
  in 
  the 
  shape 
  

   or 
  character 
  of 
  the 
  teeth 
  could 
  be 
  made 
  out, 
  and 
  beyond 
  three 
  cases 
  

   with 
  multicuspid 
  centrals 
  there 
  seemed 
  to 
  be 
  no 
  gross 
  variations; 
  for 
  

   numerical 
  examination 
  the 
  length 
  of 
  the 
  radula 
  and 
  the 
  number 
  of 
  

   transverse 
  rows 
  of 
  teeth 
  were 
  determined. 
  The 
  length 
  is 
  given 
  in 
  

   arbitrary 
  units, 
  12'8 
  of 
  which 
  equal 
  1 
  mm. 
  

  

  ^ 
  The 
  weights 
  are 
  nearly 
  proportional 
  to 
  the 
  calculated 
  shell 
  volumes, 
  the 
  ratio 
  

   volume 
  to 
  weight 
  varying 
  only 
  from 
  2-5 
  to 
  2-6 
  on 
  passing 
  from 
  the 
  smallest 
  

   males 
  to 
  the 
  largest 
  females. 
  

  

  