﻿■ 
  NEWTON: 
  ON 
  ANODONTA 
  BECKLESI, 
  N.SP., 
  ETC. 
  115 
  

  

  the 
  remaining 
  types 
  are 
  preserved 
  in 
  the 
  British 
  Museum. 
  Although 
  

   new 
  material 
  has 
  come 
  to 
  hand 
  since 
  this 
  early 
  work 
  was 
  accomplished, 
  

   no 
  attempt 
  has 
  since 
  been 
  made 
  by 
  palaeontologists 
  in 
  this 
  country 
  

   to 
  increase 
  our 
  knowledge 
  of 
  these 
  freshwater 
  shells, 
  but 
  through 
  

   the 
  researches 
  of 
  Koch,^ 
  Dunker,- 
  Struckmann,^ 
  Parent,* 
  and 
  others, 
  

   we 
  learn 
  that 
  some 
  of 
  the 
  English 
  species 
  of 
  Unio 
  are 
  closely 
  

   related 
  to 
  certain 
  forms 
  found 
  in 
  the 
  Wealden 
  areas 
  of 
  Germany, 
  

   France, 
  etc. 
  

  

  The 
  Spanish 
  Wealden 
  beds 
  also 
  exhibit 
  a 
  similar 
  resemblance, 
  

   Messrs. 
  Palacios 
  & 
  Sanchez^ 
  having 
  discovered 
  a 
  large 
  Unio 
  showing- 
  

   affinities 
  with 
  the 
  English 
  Valdensis. 
  

  

  With 
  regard 
  to 
  the 
  genus 
  Anodonta, 
  one 
  of 
  the 
  edentulous 
  members 
  

   of 
  the 
  TJnionidse, 
  it 
  may 
  be 
  said 
  to 
  be 
  of 
  particulaiiy 
  rare 
  occurrence 
  

   in 
  rocks 
  of 
  Mesozoic 
  age, 
  and 
  the 
  species 
  about 
  to 
  be 
  described 
  from 
  

   the 
  Wealden 
  strata 
  is 
  probably 
  the 
  oldest 
  authentically 
  known 
  from 
  

   this 
  or 
  any 
  other 
  country. 
  Certain 
  species 
  have 
  been 
  published 
  which 
  

   have 
  since 
  been 
  relegated 
  to 
  other 
  genera, 
  as 
  for 
  instance 
  Quenstedt's 
  ^ 
  

   Ajiodonta 
  lettica, 
  as 
  well 
  as 
  arenacea 
  and 
  diihia 
  of 
  Oscar 
  Fraas,' 
  all 
  

   from 
  the 
  German 
  Trias, 
  which 
  Alberti^ 
  has 
  recognized 
  as 
  belonging 
  

   to 
  his 
  genus 
  Anoplojihora. 
  

  

  Again, 
  Matheron's^ 
  U. 
  Gardanensis, 
  from 
  the 
  uppermost 
  French 
  

   Cretaceous, 
  although 
  placed 
  by 
  some 
  authors 
  in 
  Anodonta, 
  is 
  more 
  

   probably 
  a 
  form 
  of 
  Sjjatka, 
  as 
  suggested 
  by 
  Sandberger.^" 
  The 
  latest 
  

   Cretaceous 
  beds 
  (Laramie 
  Group) 
  of 
  North 
  America 
  have, 
  however, 
  

   produced 
  a 
  well 
  -recognized 
  form 
  of 
  the 
  genus 
  in 
  Anodonta 
  propatoris 
  

   of 
  C. 
  A. 
  White," 
  which 
  is 
  said 
  to 
  have 
  the 
  general 
  aspect 
  of 
  modern 
  

   types 
  of 
  this 
  genus 
  as 
  found 
  in 
  the 
  rivers 
  of 
  that 
  countrj^ 
  

  

  In 
  Palaeozoic 
  times 
  there 
  thrived 
  a 
  large 
  freshwater 
  shell 
  which 
  

   had 
  been 
  described 
  by 
  W. 
  H. 
  Baily 
  as 
  Anodo7ita 
  Jukesi, 
  but 
  which 
  

   has 
  since 
  been 
  recognized 
  under 
  the 
  genus 
  Archanodon 
  of 
  Howse.^'^ 
  

  

  Ludwig 
  '^ 
  has 
  reported 
  a 
  number 
  of 
  shells 
  as 
  Anodonta 
  from 
  the 
  

   Palaeozoic 
  freshwater 
  deposits 
  of 
  the 
  Oural 
  country, 
  but 
  from 
  an 
  

  

  1 
  Koch 
  & 
  Dunker, 
  Beitrage 
  Norddeutschen 
  Oolithgebildes 
  Versteinerungen, 
  1837, 
  

  

  pp. 
  58-9, 
  pi. 
  vii. 
  

   - 
  Dunker, 
  Monographie 
  Norddeutschen 
  Wealdenbildung, 
  1846, 
  pi. 
  xi, 
  pp. 
  26-8. 
  

   ' 
  Struckmann, 
  Die 
  "Wealden 
  -JBildungen 
  von 
  Hannover, 
  1880, 
  pis. 
  i, 
  ii, 
  pp. 
  64-70. 
  

   * 
  Parent, 
  " 
  Le 
  Wealdien 
  du 
  Bas-Boulonnais 
  " 
  : 
  Ann. 
  Soc. 
  Geol. 
  Nord,1893, 
  vol. 
  xxi, 
  

  

  p. 
  60. 
  

   5 
  Palacios 
  & 
  Sanchez, 
  "La 
  Formacion 
  Wealdense 
  Soria 
  y 
  Logrono 
  " 
  : 
  Bol. 
  Coni- 
  

  

  mapa 
  Geol. 
  Espana, 
  1885, 
  vol. 
  xii, 
  pp. 
  136-8, 
  pis. 
  vi, 
  vii. 
  

   ^ 
  Handbuch 
  der 
  Petrefactenkunde, 
  1852, 
  pi. 
  xliv, 
  fig. 
  16, 
  p. 
  529. 
  

   '' 
  Oscar 
  Fraas, 
  " 
  Ueber 
  /Jfiwiowo^its 
  uud 
  einige 
  Keuper-Conchylien 
  " 
  : 
  Wiirttem- 
  

  

  bergische 
  Nat. 
  Jahresh., 
  1861, 
  vol. 
  xvii, 
  pp. 
  81-101, 
  pi. 
  i. 
  

   8 
  F. 
  von 
  Alberti, 
  Ueberblick 
  iiber 
  die 
  Trias, 
  1864, 
  pp. 
  133-41. 
  

   ^ 
  P. 
  Matheron, 
  Catalogue 
  methodique 
  et 
  descriptif 
  des 
  Corps 
  Organises 
  Fossils, 
  

  

  Bouches-du-Rhoue, 
  1842, 
  p. 
  170, 
  pi. 
  xxiv, 
  figs. 
  4, 
  5. 
  

   '0 
  F. 
  Sandberger, 
  Die 
  Land- 
  und 
  Siisswasser-Conchylien 
  derVorwelt, 
  1871, 
  Heftiii, 
  

  

  p. 
  95. 
  

   " 
  C. 
  A. 
  White, 
  12th 
  Ann. 
  Rep. 
  U.S. 
  Geol. 
  Surv. 
  Territories 
  for 
  1878, 
  part 
  i, 
  1883, 
  

  

  p. 
  61, 
  pi. 
  xxiv, 
  fig. 
  2. 
  

  

  12 
  R. 
  Howse, 
  Nat. 
  Hist. 
  Trans. 
  Northumberland, 
  1878, 
  vol. 
  vii, 
  p. 
  173, 
  pi. 
  xiv 
  ; 
  

  

  and 
  R. 
  B. 
  Newton, 
  Geol. 
  Mag., 
  1899, 
  pp. 
  245-51. 
  

  

  13 
  Ludwig, 
  PahTDontographica, 
  1861, 
  vol. 
  x, 
  pp. 
  19-22, 
  pi. 
  iii. 
  

  

  