﻿I90 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  The 
  long-range 
  forms 
  are 
  Auicula 
  echinata, 
  Gervillia 
  acuta, 
  Lima 
  

   duplicate/,, 
  L.gibbosa, 
  Ostrea 
  acuminata, 
  O.Soiverbyi, 
  and 
  Pecten 
  vagans. 
  

   Many 
  species 
  range 
  from 
  the 
  Inferior 
  Oolite 
  to 
  the 
  Corallian 
  beds, 
  but 
  

   do 
  not 
  appear 
  in 
  the 
  Fuller's 
  Earth. 
  I 
  doubt 
  not 
  many 
  may 
  be 
  found 
  ; 
  

   but 
  not 
  being 
  part 
  of 
  the 
  Fullers-earth 
  fauna 
  I 
  cannot 
  notice 
  them. 
  

   6 
  genera 
  and 
  11 
  species 
  pass 
  to 
  the 
  G-reat 
  Oolite, 
  genera 
  and 
  6 
  

   species 
  to 
  the 
  Forest 
  Marble 
  ; 
  4 
  genera 
  and 
  4 
  species 
  also 
  occur 
  in 
  

   the 
  Cornbrash, 
  and 
  jj 
  in 
  the 
  Kellaways 
  Rock. 
  Analysis 
  need 
  not 
  be 
  

   carried 
  further, 
  though 
  only 
  one 
  species 
  appears 
  to 
  be 
  common 
  to 
  

   the 
  Fuller's 
  Earth 
  and 
  the 
  Corallian 
  beds 
  (Pecten 
  vagans). 
  9 
  spe- 
  

   cies 
  avoided 
  the 
  argillaceous 
  conditions 
  of 
  the 
  Fullers-earth 
  waters 
  ; 
  

   doubtless 
  it 
  was 
  due 
  to 
  this 
  that 
  so 
  many 
  species 
  in 
  the 
  rich 
  

   fauna 
  of 
  the 
  Inferior-Oolite 
  sea 
  so 
  suddenly 
  disappeared 
  : 
  the 
  

   Ammonites 
  dwindled 
  from 
  42 
  species 
  to 
  5, 
  the 
  Gasteropoda 
  from 
  

   41 
  genera 
  and 
  240 
  species 
  to 
  one 
  genus 
  and 
  one 
  species, 
  and 
  the 
  

   Lamellibranchs 
  from 
  02 
  genera 
  and 
  470 
  species 
  to 
  18 
  genera 
  and 
  

   :*6 
  species 
  (a 
  few 
  coming 
  in 
  to 
  swell 
  the 
  number 
  to 
  GO 
  species), 
  the 
  

   Dibranchiate 
  Cephalopoda 
  through 
  the 
  Belcmnites 
  from 
  10 
  species 
  

   to 
  13. 
  No 
  Xautilus 
  seems 
  to 
  have 
  loved 
  the 
  Fuller's-earth 
  sea 
  ; 
  

   out 
  of 
  the 
  6 
  species 
  in 
  the 
  Inferior 
  Oolite 
  none 
  again 
  appeared. 
  

   This 
  decrease 
  from 
  so 
  prolific 
  a 
  fauna 
  could 
  only 
  be 
  due 
  to 
  physical 
  

   causes 
  ; 
  and 
  probably 
  a 
  locally 
  deep-sea 
  condition 
  prevailed 
  at 
  the 
  

   close 
  of 
  the 
  Inferior-Oolite 
  period, 
  and 
  with 
  it 
  a 
  corresponding- 
  

   migration 
  of 
  those 
  beings 
  fitted 
  to 
  the 
  new 
  condition 
  of 
  things 
  took 
  

   place. 
  

  

  Dimyaria. 
  — 
  22 
  genera 
  and 
  51 
  species 
  occur 
  in 
  the 
  Fuller's 
  Earth, 
  

   \ 
  I 
  of 
  which 
  are 
  Inferior-Oolite 
  forms 
  ; 
  so 
  that, 
  as 
  in 
  the 
  group 
  

   Monomyaria, 
  50 
  per 
  cent, 
  passed 
  up 
  from 
  the 
  beds 
  below. 
  These 
  are 
  

   mostly 
  moderately 
  deep-sea 
  forms, 
  such 
  as 
  Trigonia, 
  TJiracia, 
  Pho- 
  

   ladomya, 
  Nucula, 
  Myacites, 
  Modiola, 
  Homomya, 
  CucuUcea, 
  Anatina, 
  

   &c 
  10 
  genera 
  and 
  30 
  species 
  passed 
  to 
  the 
  Great 
  Oolite, 
  only 
  

   \ 
  to 
  the 
  shallow-water 
  deposits 
  of 
  the 
  Forest 
  Marble, 
  } 
  \ 
  to 
  the 
  Corn- 
  

   brash, 
  § 
  to 
  the 
  Kellaways 
  Hock, 
  jj 
  to 
  the 
  Oxford 
  Clay, 
  and 
  J 
  to 
  the 
  

   Corallian 
  beds 
  ; 
  these 
  occurrences 
  in 
  the 
  higher 
  beds 
  are 
  through 
  

   long-range 
  species 
  that 
  appear 
  only 
  intermittently, 
  conditions 
  not 
  

   suiting 
  them. 
  

  

  Gasteropoda. 
  — 
  It 
  seems 
  incredible 
  that 
  a 
  subformation 
  standing 
  

   between 
  two 
  such 
  prolific 
  horizons 
  as 
  the 
  Inferior 
  Oolite 
  and 
  Great 
  

   Oolite 
  (the 
  former 
  possessing 
  fy 
  species, 
  and 
  the 
  latter 
  2 
  4 
  4 
  ° 
  7 
  species) 
  

   should 
  yield 
  only 
  one 
  species 
  ; 
  but 
  I 
  know 
  of 
  no 
  other 
  Gasteropod 
  

   than 
  Maria 
  Phillipsii 
  that 
  bridged 
  over 
  the 
  time 
  occupied 
  in 
  the 
  

   deposition 
  of 
  the 
  Fuller's-earth 
  clays 
  ; 
  and 
  this 
  species, 
  first 
  appear- 
  

   ing 
  in 
  the 
  Inferior 
  Oolite, 
  died 
  out 
  in 
  the 
  Great 
  Oolite. 
  Yet 
  |§ 
  

   species 
  lived 
  on 
  from 
  the 
  Inferior 
  Oolite 
  somewhere 
  during 
  the 
  long 
  

   change, 
  and 
  appeared 
  again 
  in 
  the 
  Great 
  Oolite 
  ; 
  possibly 
  such 
  a 
  

   total 
  removal 
  or 
  migration 
  of 
  a 
  great 
  group 
  is 
  paralleled 
  nowhere 
  in 
  

   the 
  British 
  rocks 
  during 
  any 
  period 
  of 
  their 
  long 
  history. 
  

  

  Cephalopoda. 
  — 
  Ammonites. 
  — 
  Am. 
  bijlexuosus, 
  Am. 
  discus, 
  Am. 
  

   fuscus, 
  Am. 
  Herveyi, 
  and 
  Am. 
  viator 
  are 
  the 
  only 
  5 
  species 
  known. 
  

   The 
  zone 
  of 
  Am. 
  ParJcinsoni 
  did 
  not 
  transmit 
  its 
  rich 
  contents 
  to 
  

  

  

  