﻿74 
  PROCEEDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  f^OCIETY. 
  

  

  the 
  diameter 
  of 
  the 
  ovicapsule, 
  which 
  varies 
  hetween 
  10 
  and 
  15 
  mm. 
  

   The 
  ovicapsule 
  is 
  whitish, 
  calcareous, 
  consisting 
  chiefly 
  of 
  carbonate 
  

   of 
  lime, 
  Avith 
  a 
  smooth 
  surface, 
  thickness 
  about 
  -5 
  mm. 
  The 
  inside 
  

   is 
  lined 
  all 
  round 
  with 
  a 
  thin, 
  light-brown 
  membrane 
  of 
  conchyolin. 
  

   Under 
  the 
  microscope 
  the 
  calcareous 
  layer 
  shows 
  numerous 
  minute 
  

   pores, 
  but 
  these 
  are 
  lacking 
  on 
  the 
  inner 
  membrane. 
  

  

  An 
  interesting 
  fact 
  is 
  that 
  one 
  of 
  these 
  ovicapsules 
  has 
  turned 
  up 
  

   fossil 
  in 
  the 
  Otekaieke 
  limestone. 
  Station 
  Peak, 
  Waitaki 
  Valley, 
  

   South 
  Island 
  of 
  New 
  Zealand 
  (loc. 
  477 
  of 
  the 
  N. 
  Zeal. 
  Geological 
  

   Survey). 
  The 
  limestone 
  belongs 
  to 
  the 
  Ototaran 
  Stage 
  of 
  the 
  

   Oamaruian 
  Group. 
  The 
  ovicapsule 
  is 
  fixed 
  on 
  a 
  bivalve 
  shell, 
  semi- 
  

   globose, 
  diameter 
  11mm., 
  lieight 
  4 
  mm. 
  This 
  is 
  the 
  first 
  fossil 
  

   ovicapsule 
  of 
  Alcithoe 
  I 
  have 
  come 
  across. 
  

  

  27te 
  embryonic 
  shell, 
  magnified 
  

   figures 
  of 
  which 
  are 
  here 
  reproduced, 
  

   of 
  A. 
  arahica, 
  sub-sp. 
  elongata, 
  is 
  cal- 
  

   careous, 
  thin 
  and 
  fragile, 
  cinereous, 
  

   sometimes 
  with 
  a 
  few 
  brown 
  zigzag 
  

   markings 
  near 
  the 
  outer 
  lip, 
  of 
  1h 
  

   convex 
  whorls, 
  the 
  first 
  smooth, 
  the 
  

   3 
  ^^^ 
  '/ 
  succeeding 
  \h 
  volutions 
  with 
  sub- 
  

   "ip" 
  \ 
  / 
  equidistant 
  strong 
  incremental 
  lines, 
  

  

  crossed 
  by 
  rather 
  distant 
  linear 
  spiral 
  

   grooves. 
  Outer 
  lip 
  sharp, 
  columella 
  with 
  two 
  to 
  four 
  oblique 
  plaits. 
  

   Ease 
  of 
  the 
  short 
  canal 
  faintly 
  notched. 
  Height 
  8 
  mm., 
  diameter 
  

   4-2 
  mm. 
  

  

  Mode 
  of 
  procuring 
  food. 
  — 
  Mr. 
  W. 
  Traill 
  made 
  the 
  observation 
  that 
  

   some 
  specimens 
  of 
  Alcithoe 
  wlien 
  taken 
  oiat 
  of 
  tlie 
  water 
  held 
  a 
  small 
  

   bivalve 
  {Soletellina, 
  Mesodesina, 
  etc.), 
  letaining 
  tlie 
  animal 
  tightly 
  

   between 
  the 
  folds 
  of 
  the 
  foot 
  and 
  close 
  to 
  the 
  mouth. 
  He 
  wanted 
  to 
  

   know 
  how 
  these 
  bivalves 
  were 
  killed, 
  and 
  asked 
  for 
  information 
  or 
  

   the 
  suggestion 
  of 
  further 
  experiments. 
  Kemembering 
  that 
  all 
  the 
  

   Stenoglossa 
  possess 
  an 
  unpaired 
  oesophageal 
  gland, 
  the 
  gland 
  of 
  

   Leiblein 
  or 
  poison-gland, 
  which 
  secretes 
  sulphuric 
  acid 
  (in 
  some 
  

   cases 
  up 
  to 
  4| 
  per 
  cent), 
  I 
  sent 
  Mr. 
  Traill 
  some 
  blue 
  litmus 
  paper, 
  

   and 
  asked 
  him 
  to 
  apply 
  it 
  to 
  the 
  buccal 
  secretions 
  as 
  soon 
  as 
  the 
  

   Alcithoe 
  was 
  taken 
  out 
  of 
  the 
  water. 
  Tlie 
  result 
  was 
  that 
  tlie 
  litmus 
  

   paper 
  was 
  turned 
  red 
  at 
  once, 
  proving 
  the 
  presence 
  of 
  an 
  acid. 
  It 
  is 
  

   held 
  that 
  the 
  sulphuric 
  acid 
  serves 
  to 
  dissolve 
  the 
  calcareous 
  spicules 
  

   of 
  the 
  animals 
  taken 
  as 
  food, 
  but 
  in 
  this 
  instance 
  it 
  is 
  reasonable 
  to 
  

   admit 
  that 
  it 
  helps 
  to 
  kill 
  the 
  animal 
  of 
  the 
  bivalve. 
  Suffocation 
  

   alone 
  is 
  no 
  doubt 
  a 
  somewhat 
  slow 
  process 
  to 
  produce 
  the 
  relaxation 
  

   of 
  the 
  adductor 
  muscles, 
  followed 
  by 
  opening 
  of 
  the 
  valves 
  and 
  

   extraction 
  of 
  the 
  animal 
  by 
  means 
  of 
  the 
  radula. 
  In 
  Gastropods 
  

   such 
  as 
  Natica, 
  Miirex, 
  Trophon., 
  Thais, 
  etc., 
  Avhich 
  bore 
  holes 
  into 
  the 
  

   shells 
  of 
  other 
  marine 
  molluscs, 
  the 
  secretion 
  of 
  acid 
  no 
  doubt 
  

   greatly 
  facilitates 
  the 
  action 
  of' 
  the 
  radula. 
  

  

  