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  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  los 
  

  

  Japan, 
  sent 
  to 
  the 
  U. 
  S, 
  National 
  Museum 
  a 
  few 
  years 
  ago 
  by 
  Captain 
  

   Honess, 
  U. 
  S. 
  Army 
  Sanitary 
  Corps, 
  conclusively 
  demonstrated 
  that 
  

   this 
  species 
  is 
  ovoviviparous, 
  as 
  previously 
  suspected. 
  The 
  head 
  and 
  

   snout 
  of 
  these 
  snails 
  are 
  uncomplicated 
  in 
  either 
  sex 
  by 
  external 
  re- 
  

   productive 
  structures 
  of 
  any 
  kind. 
  Coitus 
  is 
  probably 
  accomplished 
  

   by 
  apposition 
  of 
  the 
  mantle 
  edges, 
  with 
  perhaps 
  some 
  prolapsis 
  of 
  the 
  

   genital 
  duct 
  openings. 
  The 
  lower 
  part 
  of 
  the 
  female 
  reproductive 
  

   duct 
  (oviduct) 
  is 
  enlarged 
  to 
  form 
  a 
  functional 
  uterus. 
  It 
  is 
  thin- 
  

   walled 
  when 
  fully 
  distended 
  with 
  young 
  and 
  apparently 
  is 
  not 
  glandu- 
  

   lar. 
  The 
  hundreds 
  of 
  embryonic 
  young 
  of 
  uniformly 
  small 
  size 
  

   developed 
  at 
  one 
  time 
  appear 
  to 
  be 
  packed 
  in 
  axial 
  rows, 
  visible 
  ex- 
  

   ternally 
  when 
  the 
  animal 
  is 
  removed 
  from 
  the 
  shell 
  and 
  resembling 
  

   the 
  conglutinates 
  of 
  glochidia 
  of 
  the 
  North 
  American 
  fresh-water 
  

   mussel 
  genus 
  Strophitus. 
  In 
  some 
  cases 
  the 
  young 
  nearest 
  the 
  ovi- 
  

   duct 
  are 
  not 
  fuUy 
  developed, 
  showing 
  that 
  development 
  of 
  the 
  ova 
  is 
  

   at 
  least 
  partly 
  progressive 
  as 
  the 
  young 
  approach 
  the 
  uterine 
  mouth. 
  

   On 
  the 
  other 
  hand, 
  the 
  great 
  uniformity 
  of 
  size 
  of 
  all 
  the 
  fully 
  de- 
  

   veloped 
  young, 
  with 
  shells 
  of 
  about 
  2 
  whorls, 
  would 
  indicate 
  a 
  definite 
  

   seasonal, 
  mass 
  release 
  of 
  the 
  young. 
  At 
  any 
  rate, 
  there 
  is 
  no 
  indica- 
  

   tion 
  of 
  any 
  continued 
  growth 
  to 
  large 
  size 
  of 
  a 
  few 
  embryos 
  at 
  a 
  time 
  

   or 
  continued 
  parturition 
  over 
  a 
  long 
  season 
  or 
  throughout 
  the 
  year 
  

   as 
  in 
  certain 
  genera 
  of 
  the 
  family 
  Thiaridae. 
  

  

  Kecently, 
  Corp. 
  W. 
  E. 
  Old 
  of 
  the 
  U. 
  S. 
  Army 
  Signal 
  Corps 
  sent 
  

   four 
  species 
  of 
  "Alelania" 
  from 
  Korea 
  to 
  the 
  U. 
  S. 
  National 
  Museum. 
  

   Examination 
  of 
  the 
  animals 
  by 
  both 
  R. 
  T. 
  Abbott 
  and 
  the 
  author 
  has 
  

   proven 
  that 
  "Melania" 
  nodijila 
  Martens 
  is 
  an 
  Oxytrema 
  as 
  noted 
  above, 
  

   while 
  the 
  species 
  gottschei 
  Martens, 
  nodiperda 
  Martens, 
  and 
  graniperda 
  

   Martens 
  (1905) 
  are 
  members 
  of 
  the 
  genus 
  Semisulcospira. 
  The 
  

   geographic 
  range 
  of 
  Semisulcospira 
  across 
  continental 
  Asia 
  is 
  imper- 
  

   fectly 
  known 
  and 
  in 
  need 
  of 
  continued 
  research. 
  

  

  Family 
  Pleuroceridae 
  (in 
  Africa) 
  

  

  Subfamily 
  pleurocerinae 
  

  

  Genus 
  Potadoma 
  Swainson, 
  1840 
  

  

  The 
  genotype 
  of 
  Potadoma 
  Swainson 
  (1840, 
  pp. 
  200, 
  341), 
  P.freethii 
  

   (Gray), 
  must 
  be 
  examined 
  to 
  completely 
  clear 
  up 
  the 
  position 
  of 
  this 
  

   genus. 
  Pilsbry 
  and 
  Bequaert 
  (1927) 
  have 
  reported 
  that 
  these 
  snails 
  

   are 
  apparently 
  oviparous, 
  with 
  the 
  edge 
  of 
  the 
  mantle 
  smooth 
  and 
  even. 
  

   They 
  compare 
  these 
  species 
  to 
  some 
  species 
  of 
  the 
  American 
  genus 
  

   Pachychilus. 
  If 
  Potadoma 
  is 
  oviparous 
  as 
  reported, 
  with 
  the 
  egg-laying 
  

   groove, 
  it 
  belongs 
  in 
  the 
  subfamily 
  Pleurocerinae, 
  and 
  the 
  subfamilies 
  

  

  