﻿366 
  PROCEEDIJs'GS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIpyiY. 
  

  

  horizon 
  in 
  the 
  lowest 
  series 
  have 
  exhausted 
  their 
  ground, 
  whilst 
  at 
  the 
  same 
  

   time 
  their 
  fry 
  are 
  swimming 
  in 
  the 
  manner 
  of 
  Pteropods 
  through 
  the 
  waters. 
  

  

  " 
  The 
  adults 
  are 
  destroyed, 
  but 
  their 
  descendants 
  survive, 
  so 
  affected, 
  however, 
  

   by 
  the 
  change 
  in 
  the 
  condition 
  of 
  the 
  element 
  as 
  to 
  assume 
  a 
  new 
  form, 
  and 
  

   develope 
  themselves 
  under 
  the 
  aspect 
  of 
  distinct 
  species. 
  A 
  second 
  revolution 
  

   of 
  the 
  same 
  kind 
  brings 
  about 
  a 
  third, 
  still 
  more 
  remarkable 
  and 
  apparently 
  

   equally 
  sudden, 
  change, 
  and 
  the 
  continued 
  inroads 
  of 
  the 
  sea 
  at 
  length 
  revo- 
  

   lutionise 
  the 
  character 
  of 
  the 
  fauna, 
  introduce 
  marine 
  testacea 
  in 
  the 
  place 
  of 
  

   the 
  freshwater 
  species, 
  and 
  destroy 
  the 
  latter 
  altogether. 
  

  

  " 
  Such 
  an 
  explanation 
  is 
  consistent 
  with 
  what 
  we 
  now 
  know 
  of 
  the 
  modes 
  

   of 
  variation 
  among 
  freshwater 
  mollusca, 
  and 
  accounts 
  sufficiently 
  for 
  a 
  very 
  

   remarkable 
  palffiontological 
  phenomenon, 
  which 
  at 
  first 
  glance 
  appeared 
  to 
  

   afford 
  strong 
  support 
  to 
  the 
  notion 
  of 
  a 
  transmutation 
  of 
  species 
  in 
  time." 
  

  

  The 
  great 
  value 
  of 
  these 
  observations 
  on 
  the 
  Cos 
  shells 
  has 
  been 
  

   referred 
  to 
  from 
  time 
  to 
  time 
  by 
  various 
  writers. 
  Leonard 
  Horner, 
  

   in 
  his 
  Anniversary 
  Address 
  before 
  the 
  Geological 
  Society 
  of 
  London 
  

   in 
  1847 
  (Quart. 
  Journ. 
  Geol. 
  Soc, 
  vol. 
  iii, 
  p. 
  xlvi, 
  1847), 
  briefly 
  

   alluded 
  to 
  the 
  interesting 
  phenomenon 
  observed 
  by 
  the 
  authors 
  in 
  

   their 
  studies 
  of 
  the 
  older 
  Pliocene 
  freshwater 
  shells 
  of 
  the 
  Island 
  of 
  

   Cos. 
  Again, 
  G. 
  Wilson 
  & 
  Archibald 
  Geikie, 
  in 
  their 
  Memoir 
  of 
  Edward 
  

   Forhes, 
  1861, 
  p. 
  306, 
  made 
  mention 
  of 
  the 
  "remarkable 
  gradations 
  

   in 
  form 
  exhibited 
  by 
  species 
  of 
  Paludina 
  and 
  Neritina 
  arising 
  from 
  

   successive 
  changes 
  in 
  the 
  physical 
  character 
  of 
  the 
  area 
  in 
  which 
  these 
  

   forms 
  lived 
  ", 
  as 
  contained 
  in 
  the 
  i^esearches 
  of 
  Forbes 
  and 
  Spratt. 
  

  

  Writing 
  on 
  some 
  brackish-water 
  fossils 
  from 
  Crete 
  in 
  1864, 
  H. 
  M. 
  

   Jenkins 
  (Quart. 
  Journ. 
  Science, 
  vol. 
  i, 
  pp. 
  413-21, 
  1864) 
  stated 
  that 
  

   " 
  the 
  freshwater 
  and 
  estuarine 
  strata 
  which 
  occur 
  there 
  contain 
  fossils 
  

   exhibiting 
  remarkable 
  modifications 
  of 
  form 
  caused 
  b}' 
  the 
  more 
  or 
  

   less 
  adverse 
  influences 
  of 
  the 
  conditions 
  under 
  which 
  they 
  lived 
  . 
  . 
  . 
  

   as 
  was 
  shown 
  by 
  Professor 
  Forbes 
  ". 
  lleference 
  was 
  also 
  made 
  to 
  the 
  

   subject 
  by 
  TchihatchefE 
  ^ 
  in 
  1869. 
  

  

  A 
  few 
  years 
  later 
  Gorceix 
  began 
  his 
  geological 
  work 
  on 
  the 
  Island 
  

   of 
  Cos, 
  and 
  read 
  a 
  memoir 
  before 
  the 
  Geological 
  Society 
  of 
  France 
  

   (Bull. 
  Soc. 
  Geol. 
  France, 
  ser. 
  iir, 
  vol. 
  ii, 
  pp. 
  398-403, 
  1874), 
  in 
  which, 
  

   however, 
  no 
  mention 
  was 
  made 
  of 
  the 
  pioneer 
  work 
  of 
  Forbes 
  and 
  

   Spratt, 
  although 
  during 
  the 
  discussion 
  Tournouer 
  (who 
  subsequently 
  

   described 
  - 
  the 
  shells 
  collected 
  by 
  that 
  author) 
  reminded 
  Gorceix 
  of 
  

   the 
  early 
  studies 
  of 
  Neritina, 
  Paludina^ 
  and 
  Melanopsis 
  carried 
  out 
  by 
  

   the 
  English 
  observers. 
  

  

  Intimately 
  connected 
  with 
  this 
  subject, 
  on 
  account 
  of 
  similar 
  

   geological 
  and 
  palaeoconchological 
  characteristics, 
  were 
  the 
  studies 
  of 
  

   Neuniayr 
  & 
  Paul 
  on 
  Slavonia 
  published 
  in 
  1875 
  (as 
  pi'eviously 
  

   mentioned). 
  This 
  memoir 
  contained 
  only 
  brief 
  I'eferences 
  to 
  the 
  

   researches 
  of 
  Forbes 
  and 
  Spratt 
  on 
  the 
  Island 
  of 
  Cos, 
  the 
  importance 
  

   of 
  whose 
  views 
  on 
  the 
  modification 
  in 
  form 
  of 
  the 
  shells 
  concerned 
  

   was 
  not 
  fully 
  appreciated 
  by 
  them 
  at 
  the 
  time 
  of 
  publication 
  of 
  their 
  

   monograph, 
  a 
  fact 
  more 
  or 
  less 
  proved 
  in 
  a 
  subsequent 
  memoir 
  by 
  

   jSTeumayr, 
  " 
  Ueber 
  den 
  Geologischen 
  Ban 
  der 
  Insel 
  Kos 
  " 
  (Denksch. 
  

  

  ^ 
  AsieMineure. 
  Geologie, 
  pt. 
  iii 
  : 
  Terrain 
  Tertiaire 
  superieur, 
  pp. 
  189,190,1869. 
  

   ^ 
  E. 
  Tournouer, 
  Ann. 
  Sci. 
  Ecole 
  Norm. 
  Sup. 
  [Paris], 
  ser. 
  Ii, 
  vol. 
  v, 
  pp. 
  445-75, 
  

   pis. 
  i-iv, 
  1876. 
  

  

  