﻿59 
  

  

  NOTE. 
  

  

  The 
  occurrence 
  of 
  the 
  Larva 
  of 
  a 
  CestodeWorm 
  in 
  Polita 
  rooersi. 
  

   {Read 
  \Oth 
  March, 
  1916.) 
  — 
  In 
  January, 
  1915, 
  a 
  specimen 
  of 
  P. 
  rog'-rsi, 
  

   13. 
  B. 
  Woodw., 
  was 
  found 
  near 
  Radlett 
  (Herts) 
  which 
  showed 
  on 
  dissection 
  

   the 
  presence 
  of 
  larva3 
  of 
  some 
  cestode 
  worm 
  in 
  the 
  lower 
  part 
  of 
  the 
  liver. 
  

   The 
  cysts, 
  some 
  twenty 
  in 
  number, 
  seem 
  to 
  lie 
  free 
  in 
  the 
  cavities 
  of 
  the 
  

   liver 
  ; 
  they 
  are 
  about 
  0'4 
  mm. 
  in 
  diameter, 
  with 
  a 
  pretty 
  tough 
  outer 
  skin. 
  

   On 
  rupturmg 
  this, 
  the 
  scolex 
  is 
  delivered, 
  showing 
  a 
  bilobed 
  appearance, 
  

   with 
  the 
  head 
  sunk 
  in 
  a 
  pit 
  at 
  one 
  end. 
  There 
  are 
  numerous 
  calcareous 
  

   bodies. 
  The 
  hooks 
  are, 
  as 
  far 
  as 
  I 
  can 
  see, 
  eighteen 
  or 
  twenty 
  in 
  

   number 
  and 
  about 
  0'05 
  mm. 
  long. 
  The 
  other 
  host 
  of 
  the 
  parasite 
  is 
  

   presumably 
  something 
  which 
  eats 
  the 
  snail 
  ; 
  birds 
  and 
  voles 
  suggest 
  them- 
  

   selves. 
  The 
  foot 
  and 
  tissues 
  of 
  the 
  snail 
  had 
  the 
  peculiar 
  pinkish 
  

   appearance 
  which 
  is 
  sometimes 
  seen 
  in 
  P. 
  rogersi 
  {Lancashire 
  Naturalist, 
  

   vol. 
  vii, 
  1914, 
  p. 
  311). 
  The 
  eggs 
  of 
  the 
  tapeworm 
  can 
  evidently 
  pass 
  

   uninjured 
  through 
  the 
  masticatory 
  apparatus 
  of 
  the 
  snail, 
  which 
  affords 
  

   further 
  evidence 
  that 
  the 
  radula 
  is 
  a 
  prehensile 
  rather 
  than 
  a 
  grinding 
  

   apparatus. 
  

  

  A. 
  E. 
  Boycott. 
  

  

  P.S. 
  — 
  Since 
  writing 
  the 
  above 
  I 
  have 
  found 
  apparently 
  the 
  same 
  

   parasite 
  in 
  six 
  out 
  of 
  ten 
  specimens 
  of 
  Polita 
  cellaria 
  (the 
  scharffi, 
  

   form) 
  and 
  in 
  two 
  of 
  twenty-one 
  P. 
  nitidula 
  collected 
  in 
  August 
  at 
  

   Sopwell 
  Nunnery, 
  near 
  St. 
  Albans. 
  Mr. 
  Bowell, 
  who 
  was 
  with 
  me, 
  

   recollects 
  that 
  mouse 
  faeces 
  were 
  abundant 
  where 
  the 
  snails 
  were. 
  

   P. 
  rogersi 
  was 
  not 
  found. 
  A 
  large 
  number 
  of 
  Polita 
  have 
  been 
  

   examined 
  from 
  other 
  localities 
  in 
  South 
  Hertfordshire 
  with 
  negative 
  

   results. 
  

  

  