﻿STRATA 
  OP 
  THE 
  HAMPSHIRE 
  BASIN. 
  477 
  

  

  Colwell 
  Bay 
  in 
  the 
  position 
  which, 
  according 
  to 
  these 
  authors, 
  it 
  

   ought 
  to 
  occupy. 
  

  

  The 
  " 
  Roydon 
  zone 
  " 
  has 
  been 
  established 
  to 
  include 
  those 
  portions 
  

   of 
  the 
  Brockenhurst 
  series 
  in 
  which 
  certain 
  fossils 
  were 
  thought 
  to 
  

   be 
  absent 
  or 
  rare. 
  My 
  own 
  collections, 
  that 
  of 
  Mr. 
  Edwards 
  in 
  the 
  

   British 
  Museum, 
  and 
  one 
  made 
  by 
  Mr. 
  E. 
  Westlake 
  and 
  placed 
  at 
  

   my 
  disposal, 
  show 
  that 
  the 
  strata 
  at 
  Roydon 
  are 
  much 
  richer 
  than 
  

   Messrs. 
  Keeping 
  and 
  Tawney 
  appear 
  to 
  have 
  concluded 
  from 
  their 
  

   visit 
  to 
  the 
  locality. 
  Yon 
  Konen 
  and 
  Edwards 
  had 
  no 
  doubt 
  what- 
  

   ever 
  of 
  the 
  contemporaneity 
  of 
  the 
  Eoydon 
  and 
  Brockenhurst 
  beds 
  ; 
  

   and 
  the 
  arguments 
  by 
  which 
  it 
  has 
  been 
  endeavoured 
  to 
  separate 
  

   them 
  are 
  of 
  the 
  slightest 
  character. 
  

  

  The 
  identification 
  of 
  the 
  overlying 
  strata 
  as 
  " 
  the 
  Venus-'beii" 
  and 
  

   its 
  reference 
  to 
  tbe 
  so-called 
  Middle 
  Headon 
  are, 
  I 
  believe, 
  equally 
  

   unfounded. 
  Cytherea 
  incrassata 
  (the 
  "Venus" 
  of 
  collectors) 
  is 
  a 
  

   species 
  of 
  wide 
  range. 
  It 
  is 
  said 
  \>y 
  the 
  officers 
  of 
  the 
  Geological 
  

   Survey 
  to 
  have 
  been 
  found 
  in 
  the 
  Barton 
  Clay, 
  though 
  this 
  is 
  doubtful. 
  

   All 
  through 
  the 
  Headon 
  series, 
  however, 
  from 
  the 
  top 
  to 
  the 
  bottom, 
  

   it 
  makes 
  its 
  appearance 
  wherever 
  brackish-water 
  or 
  marine 
  conditions 
  

   occur. 
  It 
  equally 
  abounds 
  in 
  the 
  Brockenhurst 
  beds 
  and 
  the 
  Bembridge, 
  

   a 
  band 
  crowded 
  with 
  examples 
  of 
  this 
  shell 
  overlying 
  the 
  Bembridge 
  

   Limestone. 
  Before 
  the 
  time 
  of 
  Edward 
  Eorbes 
  this 
  bed 
  was 
  unhesi- 
  

   tatingly 
  accepted 
  as 
  the 
  " 
  Fmws-bed," 
  the 
  Bembridge 
  Limestone 
  

   being 
  confounded 
  with 
  that 
  of 
  Headon 
  Hill. 
  In 
  the 
  marine 
  Brocken- 
  

   hurst 
  series 
  of 
  Whitecliff 
  Bay, 
  Cytherea 
  incrassata 
  occurs 
  in 
  great 
  

   abundance 
  in 
  the 
  bottom 
  15 
  feet; 
  it 
  is 
  more 
  sparingly 
  scattered 
  in 
  the 
  

   overlying 
  45 
  feet 
  of 
  sand, 
  but 
  again 
  becomes 
  ver\ 
  r 
  abundant 
  in 
  the 
  

   overlying 
  clays, 
  its 
  abundance 
  or 
  rarity 
  being 
  clearly 
  determined 
  

   by 
  the 
  nature 
  of 
  the 
  sea-bottom 
  at 
  the 
  time. 
  Why 
  one 
  particular 
  

   portion 
  of 
  the 
  marine 
  series 
  should 
  be 
  singled 
  out 
  and 
  called 
  " 
  the 
  

   Venus-hed" 
  I 
  am 
  quite 
  at 
  a 
  loss 
  to 
  imagine. 
  A 
  considerable 
  num- 
  

   ber 
  of 
  highly 
  characteristic 
  Brockenhurst 
  forms, 
  such 
  as 
  Voluta 
  

   spinosa, 
  Strepsidura 
  armata, 
  Ostrea 
  ventilabrum, 
  Psammobia 
  com- 
  

   pressa 
  and 
  Cardita 
  deltoidea, 
  occur 
  in 
  these 
  upper 
  beds, 
  which 
  at 
  

   the 
  top 
  exhibit 
  the 
  gradual 
  return 
  to 
  freshwater 
  conditions 
  by 
  the 
  

   presence 
  of 
  Cyrena, 
  MeJania, 
  Jlelanopsis, 
  &c. 
  

  

  But 
  what 
  is 
  more 
  fatal 
  to 
  the 
  view 
  that 
  these 
  beds 
  belong 
  to 
  the 
  

   Headon 
  series, 
  or 
  zone 
  of 
  Cerithium 
  concavum, 
  is 
  that 
  the 
  charac- 
  

   teristic 
  fossils 
  of 
  that 
  horizon 
  are 
  wholly 
  wanting 
  in 
  them. 
  Ce- 
  

   rithia 
  (C. 
  pseudocinctum 
  &c.) 
  abound 
  in 
  these 
  beds 
  ; 
  but, 
  so 
  far 
  as 
  

   my 
  observations 
  go, 
  there 
  is 
  not 
  a 
  trace 
  to 
  be 
  found 
  of 
  C. 
  concavum 
  

   and 
  0. 
  ventricosum. 
  

  

  The 
  attempt 
  to 
  split 
  up 
  this 
  series 
  of 
  marine 
  strata 
  into 
  a 
  number 
  

   of 
  distinct 
  and 
  widely 
  distributed 
  fossil-beds, 
  is, 
  I 
  believe, 
  an 
  example 
  

   of 
  that 
  misleading 
  method 
  which 
  has 
  already 
  led 
  to 
  a 
  considerable 
  

   amount 
  of 
  confusion 
  in 
  the 
  case 
  of 
  the 
  Bracklesham 
  series, 
  as 
  I 
  have 
  

   already 
  pointed 
  out 
  in 
  the 
  earlier 
  part 
  of 
  this 
  paper. 
  

  

  Over 
  the 
  thickly 
  gravel-covered 
  area 
  of 
  the 
  New 
  Forest 
  it 
  is 
  quite 
  

   hopeless 
  to 
  attempt 
  to 
  follow 
  the 
  different 
  divisions 
  of 
  the 
  Eocene 
  

   and 
  Oligocene 
  series. 
  At 
  one 
  or 
  two 
  points, 
  however, 
  the 
  marine 
  

  

  