﻿82 
  REV. 
  W. 
  DOWNES 
  OX 
  THE 
  BLACKDOWN 
  BEDS. 
  

  

  Oyprina 
  cuneata 
  25 
  

  

  Exogyra 
  conica 
  20 
  

  

  Cucullsea 
  carinata 
  15 
  

  

  Cardimn 
  Hillanurn 
  7 
  

  

  Venus 
  sublsevis, 
  Cytherea 
  plana, 
  and 
  allied 
  forms 
  12 
  

  

  Cyprina 
  angulata, 
  C. 
  rostrata 
  5 
  

  

  Turritella 
  granulata 
  3 
  

  

  Cuculleea 
  fibrosa 
  (glabra) 
  3 
  

  

  Trigonia 
  scabricola 
  3 
  

  

  Thetis 
  gigantea 
  3 
  

  

  Other 
  fossils 
  4 
  

  

  100 
  

  

  1 
  found 
  in 
  all 
  46 
  species 
  in 
  this 
  bed, 
  many 
  of 
  which 
  range 
  down- 
  

   wards 
  into 
  lower 
  beds, 
  while 
  very 
  few 
  of 
  them 
  have 
  a 
  higher 
  range. 
  

  

  Bed 
  11. 
  A 
  bed 
  of 
  variegated 
  fine 
  sand 
  with 
  thin 
  lenticular 
  and 
  

   impersistent 
  shell-bands. 
  The 
  fossils 
  from 
  these 
  bands 
  are 
  mostly 
  

   broken, 
  and 
  all 
  much 
  waterworn. 
  Pectunculus 
  sublazvis 
  and 
  Tri- 
  

   gonia 
  affinis* 
  abound, 
  together 
  with 
  a 
  few 
  other 
  species 
  less 
  

   abundant. 
  It 
  is 
  about 
  18 
  feet 
  thick, 
  but 
  the 
  shell-bands 
  are 
  only 
  

   about 
  2 
  inches 
  in 
  thickness. 
  

  

  Bed 
  12. 
  Here 
  there 
  is 
  not 
  the 
  slightest 
  doubt 
  about 
  the 
  agreement 
  

   between 
  Blackdown 
  and 
  Haldon. 
  Beds 
  10 
  and 
  11 
  would 
  appear 
  to 
  

   have 
  some 
  meagre 
  representation 
  at 
  Haldon, 
  to 
  judge 
  by 
  the 
  fossils 
  

   which 
  have 
  come 
  from 
  the 
  base 
  of 
  that 
  series 
  and 
  by 
  their 
  mode 
  of 
  

   occurrence 
  in 
  it 
  ; 
  though 
  I 
  must 
  admit 
  that 
  I 
  have 
  not 
  myself 
  seen 
  

   any 
  thing 
  there 
  in 
  situ 
  which 
  I 
  could 
  positively 
  identify 
  with 
  either 
  

   of 
  them. 
  But 
  the 
  greater 
  part 
  of 
  the 
  Haldon 
  rock 
  may 
  be 
  

   without 
  hesitation 
  referred 
  to 
  this 
  bed 
  12, 
  which 
  therefore 
  develops 
  

   a 
  greater 
  thickness 
  at 
  Haldon 
  than 
  at 
  Blackdown. 
  At 
  Blackdown 
  

   it 
  is 
  about 
  25 
  feet 
  thick, 
  and 
  consists 
  of 
  sand 
  with 
  layers 
  of 
  cherty 
  

   sandstone 
  passing 
  upwards 
  into 
  chert. 
  The 
  characteristic 
  fossil 
  is 
  

   above 
  all 
  others 
  Pecten 
  quadricostahis, 
  which 
  is 
  never 
  found 
  lower 
  

   down 
  in 
  the 
  series. 
  Trigonia 
  dcedaleaf, 
  Pectunculus 
  sublcevis, 
  and 
  

   Exogyra, 
  mostly 
  broken, 
  are 
  also 
  found 
  here, 
  and 
  a 
  few 
  others; 
  but 
  

   fossils, 
  as 
  a 
  rule, 
  are 
  scarce. 
  The 
  Haldon 
  bed, 
  which 
  corresponds 
  with 
  

   it, 
  is 
  probably 
  about 
  35 
  feet 
  thick, 
  and 
  this 
  also 
  consists 
  of 
  sand 
  with 
  

   several 
  layers 
  of 
  cherty 
  sandstone. 
  Fragments 
  of 
  Pecten 
  quadricos- 
  

   tatus 
  and 
  of 
  Exogyra 
  are 
  abundant 
  in 
  it 
  at 
  Haldon 
  ; 
  but 
  I 
  could 
  find 
  

   hardly 
  any 
  thing 
  else 
  there. 
  Both 
  at 
  Blackdown 
  and 
  at 
  Haldon 
  

   fossils 
  of 
  this 
  horizon 
  are 
  commonly 
  covered 
  with 
  concentric 
  incrus- 
  

   tations 
  of 
  chalcedony, 
  exactly 
  like 
  those 
  on 
  the 
  Triassic 
  beekites 
  at 
  

   Paignton. 
  On 
  the 
  Exeter 
  road, 
  near 
  the 
  Grand 
  Stand 
  at 
  Great 
  

   Haldon 
  racecourse, 
  I 
  put 
  my 
  hand 
  into 
  a 
  rabbit-burrow, 
  about 
  3 
  

   feet 
  above 
  the 
  junction 
  with 
  Trias, 
  and 
  brought 
  out 
  fragments 
  of 
  P. 
  

   quadricostatus 
  and 
  Exogyra. 
  It 
  is 
  thus 
  evident 
  that 
  there 
  at 
  least 
  

  

  * 
  Under 
  this 
  name 
  I 
  here 
  include 
  T. 
  Icsviuscula 
  and 
  allied 
  forms, 
  which 
  are 
  

   all 
  associated 
  together 
  in 
  this 
  one 
  bed, 
  and 
  are 
  found 
  nowhere 
  else. 
  Mr. 
  D'Urban, 
  

   of 
  Exeter, 
  points 
  out 
  to 
  me 
  that 
  Dr. 
  Lycett, 
  in 
  his 
  " 
  Corrigenda 
  " 
  at 
  the 
  end 
  of 
  

   his 
  Monograph, 
  substitutes 
  the 
  specific 
  name 
  " 
  affinis 
  " 
  for 
  that 
  of 
  " 
  excentrica 
  " 
  

   used 
  in 
  the 
  text. 
  

  

  t 
  Since 
  this 
  paper 
  was 
  read, 
  I 
  have 
  found 
  one 
  which 
  apparently 
  came 
  from 
  

   a 
  lower 
  bed. 
  

  

  