﻿298 
  I' 
  HOC 
  i;i'; 
  DINGS 
  ok 
  tuk 
  malacological 
  socikty. 
  

  

  Dr. 
  Barrois,^ 
  writing 
  upon 
  tlie 
  age 
  of 
  the 
  ' 
  Folkestone 
  Beds 
  ', 
  

   identified 
  the 
  zone 
  of 
  Ammonitea 
  mammillaris 
  as 
  s3-nchronous 
  with 
  

   that 
  of 
  the 
  Paris 
  Basin, 
  which 
  he 
  regarded 
  as 
  belonging 
  to 
  the 
  Gault, 
  

   and 
  therefore 
  classed 
  tlie 
  English 
  representative 
  in 
  the 
  same 
  formation. 
  

   The 
  present 
  writer 
  in 
  1896- 
  identified 
  tlie 
  zones 
  of 
  Acanthoceras 
  

   mammUlatum 
  and 
  HopUtes 
  interruptus 
  at 
  Okeford 
  Fitzpaine, 
  in 
  

   Uorsetsliire, 
  the 
  former 
  being 
  regarded 
  as 
  the 
  oldest 
  and 
  repre- 
  

   senting 
  the 
  base 
  of 
  the 
  Albian 
  (= 
  Gault) 
  deposits, 
  and 
  the 
  latter 
  as 
  

   immediately 
  succeeding 
  it. 
  A 
  number 
  of 
  shells 
  were 
  described 
  as 
  

   being 
  associated 
  with 
  the 
  zonal 
  forms. 
  

  

  The 
  zone 
  of 
  ITopUtea 
  interniptus 
  contained 
  — 
  

  

  Cephalopoda: 
  HopUtes 
  splendens; 
  Nautilus 
  Clementinus. 
  (gastro- 
  

   poda: 
  ActcBonina 
  formosa; 
  Auchura 
  carinata 
  ; 
  Ringinella 
  inflata; 
  

   Natica 
  gaultina; 
  Scala 
  Dupiniana; 
  Solarmm 
  suhornatum. 
  Pelecy- 
  

   poda 
  : 
  CuGulloea 
  carinata; 
  Si/nci/ 
  clone 
  ma 
  orhicularis 
  ; 
  Gervillia 
  

   Forhesiana; 
  Lioceramus 
  concentricus 
  ; 
  Lima 
  parallela; 
  Mytilus 
  sub- 
  

   simplex; 
  Nuculapectinata; 
  Exogyra 
  canaliculata 
  ; 
  Pecten 
  Galliennei 
  ; 
  

   Pleiiromya 
  plicata; 
  Plioladomya 
  favrinai^.)-^ 
  Solen 
  Dupinianus; 
  

   Trigo7iia 
  aliformis, 
  archiaciana, 
  Fittoni. 
  

   The 
  above 
  Mollusca 
  contained 
  species 
  occurring 
  in 
  similarly 
  aged 
  

   deposits 
  at 
  Folkestone, 
  Black 
  Ven, 
  Cambridge, 
  Blackdown, 
  and 
  

   Hunstanton 
  (= 
  Bed 
  Chalk 
  beds), 
  as 
  well 
  as 
  in 
  Continental 
  localities. 
  

  

  The 
  zone 
  of 
  Acanthoceras 
  mnmmillatum 
  contained 
  the 
  following 
  

   shells 
  associated 
  with 
  the 
  index-form: 
  — 
  

  

  Cephalopoda: 
  Jloplifes 
  Benettianus. 
  Pelecypoda: 
  Pleuromya 
  plicata 
  ; 
  

   CucuUcea 
  carinata; 
  Ostrea 
  Leymeriei; 
  Exogyra 
  sinuata. 
  

  

  This 
  zone 
  has 
  been 
  recognized 
  at 
  Sandgate, 
  Folkestone, 
  Crockerton, 
  

   etc., 
  and 
  further 
  localities 
  in 
  France, 
  Switzerland, 
  etc. 
  

  

  It 
  may 
  be 
  here 
  mentioned 
  that 
  an 
  analogous 
  fauna 
  to 
  that 
  character- 
  

   izing 
  the 
  ordinary 
  (nmlt 
  deposits 
  of 
  this 
  country 
  is 
  found 
  in 
  the 
  

   Blackdown 
  ^ 
  and 
  Haldon 
  Beds 
  of 
  Devonshire, 
  in 
  the 
  phosphatic 
  ' 
  Gi'een- 
  

   sand' 
  of 
  Cambridge,* 
  and 
  in 
  the 
  so-called 
  'Red 
  Chalk' 
  of 
  jS'orfolk,^ 
  

   etc. 
  (Hunstanton, 
  etc.). 
  Hence 
  the 
  whole 
  of 
  these 
  strata 
  are 
  now 
  

   generally 
  included 
  in 
  the 
  Albian 
  stage 
  of 
  the 
  Cretaceous 
  Series. 
  

  

  The 
  Chalk 
  formation 
  has 
  always 
  offered 
  a 
  fascinating 
  field 
  for 
  study 
  

   because 
  of 
  the 
  many 
  varieties 
  of 
  its 
  organic 
  remains 
  and 
  their 
  

   unusually 
  good 
  preservation, 
  causes 
  which 
  have 
  contributed 
  very 
  

   largely 
  to 
  the 
  exact 
  and 
  interesting 
  zoning 
  work 
  w^hich 
  has 
  been 
  

   accomplished 
  both 
  by 
  English 
  and 
  Continental 
  palaeontologists. 
  In 
  

   the 
  different 
  schemes 
  that 
  have 
  been 
  published 
  from 
  time 
  to 
  time 
  on 
  

   this 
  subject, 
  it 
  is 
  noticeable 
  that 
  the 
  index-fossil 
  is 
  not 
  so 
  frequently 
  

  

  ^^ 
  Ann. 
  Soc. 
  Geol. 
  Nord, 
  vol. 
  iii, 
  pp. 
  23-5, 
  1876. 
  

  

  - 
  E. 
  B. 
  Newton 
  in 
  Geological 
  Magazine, 
  1896, 
  p. 
  198 
  ; 
  and 
  Proe. 
  Dorset 
  Nat. 
  

  

  Hist. 
  Antiq. 
  Field 
  Club, 
  vol. 
  xviii, 
  pp. 
  66-99, 
  pis. 
  i-iii, 
  1897. 
  

   ^ 
  W. 
  Downes, 
  Quart. 
  Journ. 
  Geol. 
  Soc, 
  vol. 
  xxxviii, 
  p. 
  75, 
  1882. 
  

   * 
  Jukes-Browne, 
  ibid., 
  vol. 
  xxxi, 
  p. 
  256, 
  1875 
  ; 
  vol. 
  xxxiii, 
  p. 
  485, 
  1877. 
  

   ■' 
  H. 
  G. 
  Seeley, 
  Ann. 
  Mag. 
  Nat. 
  Hist., 
  ser. 
  Ill, 
  vol. 
  vii, 
  p. 
  2,33, 
  1861; 
  

  

  T. 
  Wiltshire, 
  Quart. 
  Journ. 
  Geol. 
  Soc, 
  vol. 
  xx, 
  p. 
  327, 
  1864; 
  Proc 
  Geol. 
  

  

  Assoc, 
  (separately 
  published), 
  1859, 
  pp. 
  1-18, 
  pis. 
  i-iv 
  ; 
  and 
  Quart. 
  .Journ. 
  

  

  Geol. 
  Soc, 
  vol. 
  XXV, 
  p. 
  185, 
  1869. 
  

  

  