﻿30 
  PKOCKKDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIETr. 
  

  

  by 
  dilatation 
  {Sp.s.). 
  Septaria, 
  and 
  especially 
  Neritina, 
  stayed 
  in 
  

   the 
  fresh 
  water, 
  Neritina 
  going 
  farthest 
  northward; 
  in 
  this 
  way 
  

   Neritina 
  was 
  adapted 
  in 
  the 
  highest 
  degree 
  to 
  the 
  new 
  conditions, 
  

   it 
  lost 
  the 
  spermatophore, 
  transferring 
  the 
  sperm 
  freely. 
  Accordingly 
  

   there 
  no 
  sperm-sac 
  or 
  secondary 
  bursa 
  is 
  formed. 
  The 
  connecting 
  

   canal 
  between 
  the 
  receptaculum 
  and 
  thalamus 
  is 
  also 
  to 
  be 
  found 
  

   in 
  the 
  Opisthobranchia, 
  e.g. 
  Aplasia 
  (= 
  Tethys, 
  Pilsbry). 
  Many 
  

   Pulmonata 
  have 
  the 
  remains 
  of 
  it 
  in 
  the 
  diverticulum. 
  For 
  this 
  is 
  

   sometimes, 
  as 
  shown 
  by 
  Semper, 
  connected 
  with 
  the 
  upper 
  end 
  of 
  the 
  

   sperm-oviduct 
  at 
  the 
  point 
  where 
  the 
  albumen 
  gland 
  is 
  inserted. 
  

  

  There 
  is 
  still 
  to 
  be 
  explained 
  the 
  enigmatic 
  duct 
  of 
  Septaria 
  (Fig. 
  A), 
  

   the 
  enigmatic 
  duct 
  and 
  vaginal 
  canal 
  of 
  Paranerita 
  (Fig. 
  B), 
  and 
  the 
  

   organs 
  which 
  Professor 
  Bourne 
  indicates 
  in 
  Nerita 
  (Fig. 
  C, 
  Vag.c. 
  and 
  

   Sp.s'.) 
  all 
  roughly 
  dotted 
  in 
  my 
  figures. 
  The 
  latter 
  should 
  not 
  be 
  so 
  

   designated, 
  the 
  real 
  sperm-sac 
  being 
  the 
  bursa 
  sperm-sac. 
  All 
  these 
  

   things 
  seem 
  to 
  be 
  new 
  formations, 
  founded 
  on 
  mechanical 
  causes. 
  The 
  

   bursting 
  open 
  and 
  evacuation 
  of 
  the 
  spermatophore 
  is 
  connected 
  with 
  

   a 
  certain 
  swelling 
  or 
  a 
  kind 
  of 
  explosion, 
  as 
  I 
  found 
  once 
  in 
  Arion. 
  

   The 
  bursting 
  of 
  several 
  spermatophores 
  at 
  the 
  same 
  time 
  must 
  

   augment 
  the 
  pressure, 
  and 
  the 
  vaginal 
  aperture 
  being 
  closed 
  by 
  

   muscular 
  effort 
  the 
  pressure 
  must 
  take 
  another 
  way. 
  It 
  creates 
  

   the 
  enigmatic 
  duct 
  of 
  Septaria 
  (A), 
  and 
  the 
  long 
  vaginal 
  canal 
  and 
  

   enigmatic 
  duct 
  of 
  Paranerita 
  (B). 
  But 
  in 
  Nerita 
  the 
  dilatation 
  

   and 
  prolongation 
  take 
  place 
  between 
  the 
  bursa 
  or 
  receptaculum 
  and 
  

   the 
  thalamus. 
  Therefore 
  the 
  vaginal 
  canal 
  and 
  secondary 
  sperm-sac 
  

   of 
  Nerita 
  (Fig. 
  C, 
  Vag.c. 
  and 
  Sp.s'.) 
  are 
  not 
  strongly 
  homologous 
  to 
  

   the 
  dotted 
  organs 
  in 
  Figs. 
  A 
  and 
  B, 
  but 
  hemodynamic, 
  as 
  founded 
  on 
  

   the 
  same 
  functional 
  causes. 
  In 
  Figs. 
  B 
  and 
  C 
  I 
  have 
  indicated 
  the 
  

   points 
  between 
  which 
  the 
  prolongation 
  has 
  taken 
  place 
  by 
  a 
  cross 
  ( 
  + 
  ). 
  

   By 
  joining 
  the 
  two 
  points 
  the 
  normal 
  disposition 
  would 
  be 
  given. 
  

  

  Male 
  Organs. 
  

  

  The 
  great 
  prolongation 
  of 
  the 
  sperm-duct 
  is 
  not 
  rare 
  in 
  Pulmonata, 
  

   ■e.g. 
  Vaginula 
  and 
  Oncidium, 
  as 
  well 
  as 
  the 
  dilatation 
  of 
  the 
  sperm-duct 
  

   or 
  hermaphrodite 
  duct 
  in 
  the 
  distal 
  part. 
  Yet 
  the 
  prostate 
  has 
  always 
  

   another 
  aspect, 
  for 
  its 
  tubes 
  are 
  inserted 
  along 
  the 
  long 
  sperm-oviduct, 
  

   sometimes 
  at 
  intervals, 
  as 
  in 
  Agriolimax 
  or 
  Vitrina. 
  But 
  take 
  off 
  

   the 
  oviducal 
  part 
  of 
  it, 
  or 
  uterus, 
  and 
  the 
  tubes 
  will 
  approach 
  as 
  in 
  

   Nerita 
  (Fig. 
  D, 
  prs.). 
  Spermatophores 
  being 
  formed, 
  the 
  terminal 
  

   chamber 
  {t.ch.) 
  is 
  nothing 
  else 
  than 
  the 
  epiphallus, 
  and 
  the 
  basal 
  

   gland 
  is 
  a 
  flagellum. 
  Its 
  splitting 
  up 
  into 
  many 
  branches 
  is 
  not 
  

   unparalleled, 
  e.g. 
  in 
  Agriolimax. 
  

  

  It 
  is 
  quite 
  uncertain 
  if 
  the 
  cephalic 
  penis 
  was 
  originally 
  joined 
  with 
  

   the 
  genital 
  aperture 
  by 
  an 
  inner 
  vas 
  deferens 
  or 
  an 
  outer 
  sperm 
  groove, 
  

   for 
  we 
  have 
  to 
  go 
  back 
  to 
  a 
  very 
  old 
  and 
  primitive 
  stock. 
  

  

  Other 
  Organs. 
  

  

  Back 
  to 
  such 
  a 
  stock 
  points 
  also 
  the 
  oviduco-coelomic 
  funnel, 
  

   •discovered 
  by 
  Bourne. 
  Perhaps 
  he 
  is 
  not 
  right 
  in 
  concluding 
  that 
  

   the 
  genital 
  canal 
  must 
  have 
  been 
  the 
  right 
  nephridium, 
  for 
  the 
  use 
  

  

  