﻿AVEBSTER 
  : 
  EED 
  VARIETY 
  OF 
  PLANORBIS 
  CORNEUS. 
  87 
  

  

  I 
  have 
  never 
  been 
  able 
  to 
  satisfactorily 
  ascertain 
  the 
  age 
  these 
  

   snuils 
  may 
  reacli, 
  as 
  most 
  of 
  my 
  attempts 
  have 
  been 
  more 
  or 
  less 
  

   upset 
  by 
  the 
  attentions 
  of 
  Ci/pris, 
  nor 
  liave 
  I 
  been 
  able 
  to 
  observe 
  

   the 
  number 
  of 
  eggs 
  a 
  snail 
  may 
  actually 
  produce, 
  for 
  the 
  same 
  

   reason. 
  Two 
  specimens 
  of 
  cornetis, 
  two 
  years 
  old, 
  under 
  observation 
  

   from 
  the 
  1st 
  to 
  the 
  22nd 
  of 
  July 
  this 
  year, 
  laid 
  twenty-two 
  batches 
  

   of 
  eggs, 
  but 
  when 
  hatching 
  began 
  it 
  confused 
  further 
  count. 
  

  

  The 
  statement 
  that 
  freshwater 
  snails 
  are 
  in 
  the 
  habit 
  of 
  creeping 
  

   out 
  of 
  the 
  water 
  and 
  dying 
  is 
  frequently 
  met 
  with 
  in 
  books, 
  and 
  

   observers 
  are 
  warned 
  to 
  provide 
  covers 
  for 
  their 
  tanks. 
  This 
  

   precaution 
  is 
  unnecessary 
  if 
  reasonable 
  care 
  is 
  taken 
  to 
  keep 
  the 
  

   captives 
  under 
  proper 
  conditions. 
  Snails 
  do 
  not 
  like 
  a 
  new 
  home 
  

   and 
  will 
  often 
  attempt 
  to 
  escape, 
  but 
  if 
  an 
  escaped 
  snail 
  is 
  put 
  back 
  

   into 
  its 
  new 
  home 
  it 
  usually 
  accepts 
  the 
  situation 
  if 
  this 
  is 
  not 
  

   impossible. 
  When 
  snails 
  which 
  have 
  been 
  kept 
  for 
  some 
  time 
  are 
  

   found 
  above 
  the 
  water-line, 
  suspicion 
  is 
  at 
  once 
  directed 
  to 
  the 
  

   presence 
  of 
  enemies 
  or 
  foul 
  water. 
  

  

  One 
  species, 
  Lininaa 
  pereger, 
  has 
  had 
  a 
  name 
  imposed 
  upon 
  it 
  

   describing 
  it 
  as 
  a 
  restless 
  creature, 
  and 
  as 
  far 
  as 
  I 
  can 
  see 
  without 
  

   just 
  cause. 
  Whenever 
  this 
  snail 
  is 
  found 
  out 
  of 
  its 
  element 
  it 
  is 
  

   almost 
  a 
  certainty 
  that 
  the 
  water, 
  if 
  good, 
  contains 
  predatory 
  fishes. 
  

   I 
  have 
  experimentally 
  kept 
  a 
  number 
  of 
  specimens 
  of 
  L. 
  pereger 
  in 
  

   a 
  tiny 
  dish, 
  11 
  inches 
  in 
  diameter, 
  containing 
  under 
  1 
  inch 
  of 
  water, 
  

   for 
  some 
  months. 
  When 
  first 
  introduced 
  they 
  all 
  escaped 
  over 
  the 
  

   edge 
  in 
  the 
  night 
  once, 
  and 
  one 
  individual 
  twice, 
  and 
  then 
  settled 
  down. 
  

  

  L. 
  palustris 
  behaves 
  in 
  much 
  the 
  same 
  way 
  in 
  shallow 
  water. 
  

   Snails 
  subjected 
  to 
  constant 
  transference 
  from 
  one 
  vessel 
  to 
  another 
  

   get 
  accustomed 
  to 
  changes, 
  and 
  make 
  no 
  attempt 
  to 
  escape. 
  

  

  Bateman, 
  in 
  his 
  book 
  FresJmater 
  Aquaria, 
  says 
  that 
  Theodoxiis 
  

   fluviatilis 
  will 
  not 
  live 
  in 
  confinement. 
  I 
  have 
  recently 
  had 
  a 
  letter 
  

   from 
  a 
  correspondent 
  of 
  repute 
  who 
  tells 
  me 
  this 
  snail 
  has 
  thrived 
  

   for 
  years 
  in 
  his 
  aquarium. 
  It 
  is 
  highly 
  important 
  that 
  causes 
  of 
  

   failure 
  should 
  be 
  sought 
  before 
  definite 
  statements 
  are 
  recorded. 
  

  

  Since 
  I 
  have 
  a 
  good 
  many 
  Planorhis 
  collected 
  for 
  me 
  I 
  receive 
  

   quite 
  a 
  number 
  with 
  injured 
  shells, 
  and 
  consequently 
  subjects 
  for 
  

   observation. 
  Every 
  injured 
  snail 
  I 
  have 
  had 
  has 
  been 
  given 
  

   a 
  chance 
  to 
  live, 
  and 
  has 
  been 
  observed 
  closely. 
  P. 
  corneus 
  is 
  

   seldom 
  able 
  to 
  repair 
  a 
  serious 
  fracture. 
  Recently 
  I 
  have 
  observed 
  

   one 
  replace 
  quite 
  a 
  large 
  piece 
  of 
  the 
  outer 
  lip, 
  and 
  in 
  another 
  case 
  

   an 
  attempt 
  was 
  made 
  to 
  replace 
  nearly 
  the 
  whole 
  of 
  the 
  large 
  whorl. 
  

   In 
  most 
  cases 
  a 
  tiny 
  fracture 
  of 
  the 
  outer 
  lip 
  is 
  given 
  up 
  in 
  despair, 
  

   and 
  the 
  animal 
  dies. 
  A 
  fracture 
  of 
  the 
  outer 
  whorl, 
  large 
  or 
  

   small, 
  behind 
  an 
  intact 
  orifice, 
  cornetis 
  is 
  utterly 
  unable 
  to 
  repair. 
  

   I 
  have 
  witnessed 
  many 
  attempts, 
  and 
  the 
  animal 
  always 
  dies. 
  

   A 
  great 
  many 
  of 
  the 
  pond 
  snails 
  are 
  eroded 
  in 
  numerous 
  small 
  spots 
  

   which 
  in 
  time 
  become 
  perforations, 
  and 
  in 
  some 
  instances 
  mere 
  

   pinholes. 
  The 
  death 
  of 
  the 
  snail 
  always 
  occurs 
  when 
  the 
  perforation 
  

   becomes 
  complete 
  — 
  no 
  matter 
  where 
  situated. 
  From 
  this 
  evidence 
  

   it 
  is 
  very 
  strange 
  to 
  find 
  the 
  eroded 
  apex 
  of 
  the 
  r£d 
  form 
  so 
  well 
  

   mended 
  as 
  previously 
  described. 
  

  

  