﻿Vol. 
  53.] 
  OF 
  THE 
  CHALK 
  ROCK. 
  381 
  

  

  Inoceramfs 
  striates, 
  Mantell, 
  1822. 
  (PI. 
  XXVII. 
  fig. 
  13.) 
  

  

  1822. 
  Inoceramus 
  striatus, 
  G. 
  A. 
  Mantel!, 
  ' 
  Foss. 
  S. 
  Downs,' 
  p. 
  217, 
  pi. 
  xxvii. 
  f.o? 
  

   1828. 
  J. 
  de 
  C. 
  Sowerbv, 
  ' 
  Min. 
  Conch/ 
  vol. 
  vi. 
  p. 
  160, 
  pi. 
  dlxxii. 
  f 
  . 
  2 
  ; 
  1851. 
  J. 
  Morris, 
  

   * 
  Cat. 
  Brit, 
  Foss.' 
  2nd 
  ed. 
  p. 
  170 
  ; 
  1872-73. 
  H. 
  B. 
  Geinitz, 
  ' 
  DasElbthalgeb. 
  in 
  Sachsen,' 
  

   Palaeontograpbica, 
  vol. 
  xx. 
  pt. 
  i. 
  p. 
  210, 
  pi. 
  xlvi. 
  f. 
  9-13 
  ; 
  pt. 
  ii. 
  p. 
  41 
  (??pl. 
  xiii. 
  f. 
  1 
  ; 
  

   2, 
  9, 
  10). 
  

  

  Remarks. 
  — 
  The 
  specimens 
  found 
  in 
  the 
  Chalk 
  Rock 
  differ 
  from 
  

   the 
  types 
  in 
  being 
  less 
  rounded 
  — 
  they 
  are 
  higher 
  than 
  long. 
  If 
  

   this 
  character 
  be 
  constant 
  it 
  may 
  indicate 
  a 
  different 
  species, 
  but 
  

   this 
  cannot 
  be 
  determined 
  until 
  a 
  much 
  larger 
  collection 
  has 
  been 
  

   obtained. 
  At 
  present 
  I 
  have 
  seen 
  only 
  three 
  or 
  four 
  specimens 
  from 
  

   the 
  Chalk 
  Rock 
  ; 
  they 
  agree 
  in 
  form 
  with 
  some 
  which 
  were 
  col- 
  

   lected 
  from 
  the 
  Upper 
  Chalk 
  of 
  Newmarket. 
  Size 
  of 
  Chalk 
  Rock 
  

   specimens: 
  — 
  (1) 
  Length 
  = 
  24 
  mm.; 
  height 
  = 
  33 
  mm. 
  (2) 
  Length 
  

   = 
  30 
  mm. 
  ; 
  height 
  = 
  38 
  mm. 
  

  

  Both 
  Mantell's 
  and 
  Sowerby's 
  types 
  are 
  in 
  the 
  British 
  Museum 
  : 
  

   the 
  former 
  was 
  obtained 
  at 
  South 
  Street, 
  Lewes 
  ; 
  the 
  latter 
  near 
  

   Heytesbury 
  (? 
  Lower 
  or 
  Middle 
  Chalk). 
  

  

  Distribution. 
  — 
  England 
  : 
  Chalk 
  Rock 
  of 
  Roman 
  Road 
  (south-east 
  

   of 
  Calstone 
  Willington) 
  and 
  Cuckhamsley. 
  Lower, 
  and 
  perhaps 
  

   also 
  Middle 
  and 
  Upper, 
  Chalk. 
  Ireland 
  : 
  Hibernian 
  Greensand 
  — 
  - 
  

   Chloritic 
  Sandstone 
  division 
  (fide 
  Tate) 
  . 
  

  

  iNOCERAilTJS 
  Sp. 
  (PI. 
  XXVII. 
  figS. 
  14-17.) 
  

  

  Remarks. 
  —A 
  small 
  species, 
  which 
  is 
  unlike 
  any 
  described 
  form 
  

   with 
  which 
  I 
  am 
  acquainted, 
  but 
  is 
  at 
  present 
  represented 
  by 
  casts 
  

   only, 
  is 
  moderately 
  common 
  in 
  the 
  Chalk 
  Rock. 
  The 
  shell 
  is 
  rather 
  

   convex, 
  higher 
  than 
  long, 
  with 
  shallow 
  concentric 
  furrows 
  and 
  

   prominent 
  pointed 
  umbones. 
  

  

  Distribution. 
  — 
  Chalk 
  Rock 
  of 
  Lichfield 
  (Hants), 
  Winchester, 
  

   Roman 
  Road 
  south-east 
  of 
  Calstone 
  Willington, 
  Cuckhamsley, 
  

   Luton 
  cutting, 
  Wallington 
  near 
  Baldock, 
  and 
  Underwood 
  Hall 
  

   near 
  Dullingham. 
  

  

  Family 
  Ostreidse. 
  

  

  Genus 
  Ostrea, 
  Linnseus, 
  1766. 
  

  

  Ostrea 
  semiplana?, 
  Sowerby, 
  1825. 
  

  

  1825. 
  Ostrea 
  semiplana, 
  J. 
  de 
  C. 
  Sowerby, 
  'Min. 
  Concb.' 
  vol. 
  v. 
  pi. 
  cccclxxxix. 
  f 
  . 
  3. 
  

   p. 
  144. 
  

  

  Remarks. 
  — 
  The 
  genus 
  Ostrea 
  is 
  poorly 
  represented 
  in 
  the 
  Chalk 
  

   Rock. 
  The 
  specimens 
  which 
  I 
  believe 
  to 
  be 
  referable 
  to 
  0. 
  semi- 
  

   plana 
  are 
  rather 
  small, 
  and 
  this 
  probably 
  accounts 
  for 
  the 
  fact 
  that 
  

   the 
  plications 
  of 
  the 
  marginal 
  part 
  of 
  the 
  valves 
  are 
  only 
  faintly 
  

   indicated. 
  Sowerby's 
  types 
  came 
  from 
  Norwich, 
  and 
  are 
  now 
  in 
  the 
  

   British 
  Museum. 
  

  

  Distribution. 
  — 
  England 
  : 
  Upper 
  and 
  Middle 
  Chalk 
  ; 
  Chalk 
  Rock 
  

   of 
  Cuckhamsley, 
  and 
  Underwood 
  Hall 
  near 
  Dullingham. 
  Ireland 
  : 
  

   Hibernian 
  Greensand. 
  Northern 
  France 
  : 
  zone 
  of 
  T. 
  gracilis 
  in 
  the 
  

   Yonne 
  and 
  Aube, 
  zone 
  of 
  Epiaster 
  brevis 
  at 
  Thiernu, 
  zone 
  of 
  M. 
  brevi- 
  

   porus 
  at 
  Cambrai, 
  Senonian 
  of 
  the 
  neighbourhood 
  of 
  Epernay 
  and 
  

  

  