﻿ANNIVERSARY 
  ADDRESS 
  OP 
  THE 
  PRESIDENT. 
  lvii 
  

  

  new. 
  If 
  this 
  series 
  of 
  freshwater 
  beds 
  be 
  perfect, 
  I 
  confess 
  that 
  

   this 
  change 
  is 
  hard 
  to 
  account 
  for, 
  although 
  we 
  have 
  something 
  

   slightly 
  analogous 
  to 
  it, 
  for 
  example, 
  in 
  the 
  great 
  delta 
  of 
  the 
  

   Mississippi, 
  in 
  which 
  the 
  old 
  delta 
  contains 
  a 
  number 
  of 
  terrestrial 
  

   remains 
  of 
  Mammalia 
  not 
  represented 
  in 
  the 
  new. 
  It 
  may 
  be, 
  as 
  

   has 
  been 
  suggested 
  to 
  me 
  by 
  Mr. 
  Jenkins, 
  that 
  the 
  limestones 
  of 
  the 
  

   Purbeck 
  series 
  were 
  lake-deposits, 
  while 
  it 
  is 
  evident 
  to 
  every 
  one 
  

   that 
  the 
  Wealden 
  strata 
  are 
  delta-formations. 
  

  

  But, 
  however 
  this 
  may 
  be, 
  the 
  great 
  extent 
  and 
  thickness 
  (nearly 
  

   2000 
  feet) 
  of 
  these 
  deposits 
  speak 
  of 
  a 
  period 
  when 
  vast 
  neighbouring 
  

   areas 
  must 
  have 
  formed 
  a 
  continent, 
  the 
  inland 
  drainage 
  of 
  which 
  

   gave 
  birth 
  to 
  a 
  river 
  apparently 
  equal 
  to 
  the 
  largest 
  streams 
  of 
  the 
  

   living 
  world 
  ; 
  and 
  the 
  upheaval 
  of 
  that 
  land 
  to 
  afford 
  this 
  drainage, 
  

   and 
  its 
  subsequent 
  depression, 
  if 
  my 
  views 
  be 
  correct, 
  must 
  have 
  

   occupied 
  a 
  time 
  sufficiently 
  long 
  to 
  have 
  resulted 
  in 
  the 
  extinction, 
  

   by 
  migration 
  and 
  modification, 
  or 
  otherwise, 
  of 
  all 
  the 
  Oolitic 
  species, 
  

   and 
  their 
  replacement 
  by 
  migration 
  of 
  other 
  forms 
  when 
  the 
  same 
  

   area 
  was 
  reconverted 
  into 
  sea. 
  As 
  with 
  the 
  palaeozoic 
  rocks, 
  time 
  

   is 
  the 
  accompaniment 
  of 
  this 
  total 
  change 
  ; 
  and 
  if 
  we 
  adopt 
  for 
  species 
  

   and 
  genera 
  the 
  theory 
  of 
  descent 
  with 
  modification, 
  the 
  idea 
  of 
  needful 
  

   time 
  is 
  prodigiously 
  strengthened, 
  even 
  though 
  we 
  may 
  not 
  believe 
  

   that 
  all 
  the 
  Cretaceous 
  forms 
  are 
  the 
  direct 
  descendants 
  of 
  those 
  found 
  

   in 
  the 
  British 
  Oolites. 
  

  

  On 
  taking 
  a 
  general 
  view 
  of 
  the 
  Cretaceous 
  fossils 
  of 
  England, 
  

   the 
  first 
  thing 
  that 
  strikes 
  us 
  is 
  that, 
  while 
  in 
  the 
  Oolitic 
  strata 
  by 
  

   far 
  the 
  large 
  proportion 
  of 
  species 
  occur 
  in 
  the 
  Lower 
  Oolites 
  (most 
  

   of 
  these 
  being 
  in 
  the 
  Great 
  Oolite), 
  in 
  the 
  Cretaceous 
  rocks 
  the 
  

   reverse 
  is 
  the 
  case, 
  the 
  Lower 
  Greensand 
  only 
  yielding 
  280 
  known 
  

   marine 
  species, 
  and 
  the 
  upper 
  formations 
  1082, 
  while 
  of 
  these 
  no 
  

   fewer 
  than 
  521 
  occur 
  in 
  the 
  Upper 
  Chalk. 
  

  

  If, 
  going 
  further, 
  we 
  analyze 
  their 
  distribution, 
  the 
  following 
  are 
  

   some 
  of 
  the 
  chief 
  results 
  drawn 
  from 
  Table 
  Y. 
  : 
  — 
  

  

  Fourteen 
  species 
  of 
  Sponges 
  are 
  known 
  in 
  the 
  Lower 
  Greensand, 
  

   only 
  three 
  of 
  which 
  pass 
  upwards, 
  namely, 
  two 
  into 
  the 
  Upper 
  Green- 
  

   sand 
  and 
  one 
  into 
  the 
  Chalk. 
  The 
  two 
  known 
  species 
  of 
  Corals 
  are 
  

   peculiar 
  to 
  the 
  formation 
  ; 
  and 
  of 
  10 
  Echinodermata, 
  only 
  two 
  pass 
  

   upward, 
  one 
  of 
  these 
  being 
  one 
  of 
  8 
  species 
  known 
  in 
  the 
  Gault. 
  

   Of 
  10 
  species 
  belonging 
  to 
  the 
  Articulata, 
  4 
  pass 
  into 
  the 
  Gault 
  ; 
  

   while 
  of 
  26 
  Polyzoa, 
  5, 
  or 
  19 
  per 
  cent., 
  pass 
  into 
  higher 
  horizons. 
  

   Twenty-five 
  species 
  of 
  Brachiopoda 
  are 
  known 
  in 
  the 
  Lower 
  Green- 
  

   sand, 
  7 
  (24 
  per 
  cent.) 
  of 
  which 
  pass 
  upward, 
  1 
  into 
  the 
  Gault, 
  the 
  

   others 
  into 
  higher 
  horizons. 
  Of 
  49 
  species 
  of 
  Monomyaria, 
  10, 
  or 
  

   20 
  per 
  cent., 
  pass 
  upward 
  ; 
  while, 
  of 
  82 
  Dimyaria, 
  only 
  9, 
  or 
  about 
  

   11 
  per 
  cent., 
  survive 
  in 
  higher 
  formations 
  ; 
  in 
  other 
  words, 
  the 
  larger 
  

   proportion 
  of 
  the 
  deep-sea 
  forms 
  remain. 
  Of 
  30 
  species 
  of 
  Gaste- 
  

   ropoda, 
  5, 
  or 
  nearly 
  17 
  per 
  cent., 
  are 
  found 
  in 
  younger 
  strata. 
  It 
  

   thus 
  happens 
  that, 
  of 
  186 
  bivalve 
  and 
  univalve 
  Shells, 
  31, 
  or 
  about 
  

   16f 
  per 
  cent., 
  pass 
  upward. 
  Of 
  28 
  Cephalopoda, 
  5 
  (18 
  per 
  cent.) 
  

   pass 
  upward, 
  and 
  23 
  are 
  peculiar 
  to 
  the 
  Lower 
  Greensand. 
  No 
  

   Eishes 
  are 
  known 
  in 
  it 
  ; 
  and 
  of 
  4 
  Reptiles, 
  one 
  is 
  found 
  in 
  the 
  Chalk. 
  

  

  