﻿I 
  

  

  112 
  PROCEEDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIETY. 
  

  

  Thames. 
  But 
  from 
  the 
  Serpentine 
  in 
  Hyde 
  Park, 
  which, 
  as 
  far 
  as 
  

   I 
  know, 
  is 
  connected 
  with 
  the 
  Thames, 
  I 
  have 
  A. 
  Cellensis, 
  var. 
  cygnea. 
  

   In 
  conclusion, 
  I 
  may 
  mention 
  that 
  theUnionidse 
  of 
  the 
  Thames 
  have 
  

   a 
  great 
  resemhlance 
  to 
  those 
  of 
  the 
  Rhine, 
  so 
  that 
  zoogeographers 
  can 
  

   confirm 
  the 
  assumption 
  of 
  geographers 
  and 
  geologists, 
  that 
  previous 
  

   to 
  the 
  formation 
  of 
  the 
  German 
  Ocean 
  the 
  Thames 
  was 
  a 
  left 
  tributary 
  

   of 
  the 
  Ehine. 
  For 
  further 
  details 
  I 
  would 
  refer 
  to 
  my 
  article, 
  

   already 
  alluded 
  to, 
  where 
  this 
  question 
  is 
  further 
  elaborated. 
  This 
  

   short 
  article 
  must 
  not 
  be 
  considered 
  a 
  monograph 
  of 
  the 
  Naiades 
  of 
  

   the 
  Thames 
  ; 
  it 
  is 
  simply 
  intended 
  to 
  fix 
  the 
  distribution 
  in 
  England 
  

   of 
  the 
  four 
  North 
  European 
  genera 
  of 
  Naiades, 
  in 
  order 
  to 
  prepare 
  

   the 
  way 
  for 
  a 
  real 
  monograph 
  of 
  the 
  Unionidse 
  of 
  the 
  British 
  Isles, 
  J 
  

   based 
  on 
  zoogeographical 
  data. 
  It 
  will 
  be 
  a 
  great 
  source 
  of 
  satisfaction 
  : 
  

   to 
  me 
  if 
  these 
  remarks 
  should 
  stimulate 
  an 
  interest 
  for 
  the 
  TJnionidae 
  

   in 
  England, 
  and 
  be 
  the 
  means 
  of 
  obtaining 
  some 
  converts 
  on 
  the 
  other 
  

   side 
  of 
  the 
  British 
  Channel 
  for 
  my 
  distinguished 
  friend 
  and 
  teacher, 
  

   Dr. 
  Kobelt, 
  founder 
  of 
  the 
  comparative 
  investigation 
  of 
  rivers 
  b;^ 
  

   means 
  of 
  the 
  Unionidae,^ 
  who 
  this 
  year, 
  on 
  February 
  20th, 
  celebrate^ 
  

   his 
  70th 
  birthday. 
  

  

  1 
  Kobelt, 
  jSTachr. 
  Blatt. 
  Deutseh. 
  Malak. 
  Ges., 
  1908, 
  p. 
  49. 
  

  

  