﻿28 
  

  

  PROCEEDINGS 
  OF 
  THE 
  MALA,COLOGIC.VL 
  SOCIETr. 
  

  

  (vt.^.) 
  is 
  the 
  albumen 
  gland 
  of 
  authors. 
  The 
  other 
  glands 
  of 
  the 
  

   ootyi)e 
  are 
  highly 
  differentiated, 
  more 
  than 
  in 
  the 
  Pulmonata. 
  This 
  

   is 
  in 
  connexion 
  with 
  the 
  more 
  complicated 
  spawn. 
  In 
  the 
  Stylom- 
  

   matophora 
  there 
  is 
  only 
  the 
  egg-shell, 
  in 
  the 
  Basommatophora 
  the 
  

   eggs 
  are 
  bound 
  together 
  by 
  mucus, 
  but 
  in 
  the 
  Neritidae 
  the 
  spawn 
  

   is 
  enclosed 
  in 
  a 
  firm 
  capsule, 
  needing 
  a 
  new 
  glandular 
  differentiation 
  

   for 
  itself, 
  as 
  I 
  have 
  already 
  pointed 
  out 
  in 
  the 
  Bronn 
  Mollusca. 
  

  

  -t/uli. 
  

  

  Bourne 
  thinks 
  that 
  the 
  crystal 
  sac 
  is 
  a 
  shell-gland, 
  the 
  chalk 
  con- 
  

   cretions 
  of 
  it 
  being 
  applied 
  in 
  forming 
  tlie 
  spawn 
  capsule, 
  but 
  this 
  

   IS 
  _a_ 
  hypothesis 
  without 
  observation, 
  as 
  he 
  says 
  himself. 
  In 
  my 
  

   opinion 
  the 
  crystal 
  sac 
  is 
  only 
  a 
  Pulmonate 
  dart-sac, 
  which 
  ceased 
  to 
  

   act 
  when 
  the 
  terrestrial 
  ancestors 
  were 
  submerged 
  under 
  water. 
  

  

  