﻿390 
  MR. 
  H. 
  WOODS 
  ON 
  THE 
  MOLLUSCA 
  [Aug. 
  1 
  897, 
  

  

  Family 
  Astartidse, 
  Gray. 
  

   Genus 
  Caedita, 
  Bruguiere, 
  1789. 
  

   Cakdita 
  cancellata, 
  sp. 
  no 
  v. 
  (PI. 
  XXVIII. 
  figs. 
  2-5.) 
  

  

  Cf. 
  C. 
  tenuicosta, 
  F. 
  Notling 
  (non 
  Sowerby), 
  ' 
  Die 
  Fauna 
  der 
  baltisch. 
  Cenoman- 
  

   Geschiebe,' 
  Palaont. 
  Abhandl. 
  vol. 
  ii. 
  (1885) 
  p. 
  29 
  & 
  pi. 
  v. 
  f. 
  4; 
  and 
  Geinitz, 
  'Das 
  

   Elbthalgebirge 
  in 
  Sachsen,' 
  Palagontographica, 
  vol. 
  xx. 
  pt. 
  ii. 
  pi. 
  xvii. 
  f. 
  11-13. 
  

  

  Description. 
  — 
  Shell 
  oval, 
  somewhat 
  inflated, 
  with 
  the 
  part 
  from 
  

   the 
  umbo 
  to 
  the 
  posterior 
  margin 
  slightly 
  depressed 
  ; 
  a 
  little 
  longer 
  

   than 
  high. 
  Anterior 
  side 
  shorter 
  and 
  smaller 
  than 
  the 
  posterior. 
  

   Ventral 
  margin 
  curved. 
  Ornamentation 
  cancellated, 
  consisting 
  of 
  

   numerous 
  concentric 
  and 
  radiating 
  ribs 
  — 
  the 
  two 
  sets 
  being 
  of 
  about 
  

   equal 
  size. 
  Size 
  of 
  an 
  average 
  specimen 
  : 
  length 
  = 
  16 
  mm.; 
  height 
  

   = 
  14 
  mm. 
  

  

  Remarks. 
  — 
  This 
  is 
  a 
  fairly 
  common 
  species 
  at 
  Cuckhamsley, 
  but 
  

   seems 
  to 
  be 
  rare 
  in 
  other 
  places. 
  

  

  Affinities. 
  — 
  This 
  species 
  is 
  related 
  to 
  C. 
  tenuicosta, 
  Sowerby, 
  

   found 
  in 
  the 
  Gault, 
  but 
  that 
  form 
  has 
  a 
  more 
  quadrangular 
  and 
  

   compressed 
  shell, 
  and 
  its 
  ornamentation 
  consists 
  of 
  radiating 
  ribs 
  

   only, 
  crossed 
  by 
  growth-lines. 
  

  

  Distribution. 
  — 
  Chalk 
  Rock 
  of 
  Cuckhamsley, 
  Thickthorn 
  Hill 
  

   (Bledlow), 
  and 
  Luton. 
  

  

  Family 
  Arcticidse, 
  Newton. 
  

  

  Genus 
  Aectica, 
  Schumacher, 
  1817. 
  

  

  Aectica 
  quadrata 
  (d'Orbigny), 
  1843. 
  (PL 
  XXVII. 
  fig. 
  25; 
  

   PI. 
  XXVIII. 
  fig. 
  1.) 
  

  

  1840. 
  Isocardia 
  cretacea, 
  H. 
  B. 
  Geinitz, 
  ' 
  Char. 
  d. 
  Schicht. 
  u. 
  Petref. 
  des 
  sachs. 
  

   Kreidegeb.' 
  pt. 
  ii. 
  p. 
  53, 
  pi. 
  xi. 
  f 
  . 
  6 
  & 
  7. 
  

  

  1843. 
  Cyprina 
  quadrata, 
  A. 
  d'Orbigny, 
  ' 
  Pal. 
  Franc. 
  Terr. 
  Cret.' 
  vol. 
  iii. 
  p. 
  104, 
  

   pi. 
  cclxxvi'. 
  ; 
  1850. 
  A. 
  d'Orbigny, 
  ' 
  Prodr. 
  de 
  Pal.' 
  p. 
  161 
  ; 
  1850. 
  H. 
  B. 
  Geinitz, 
  ' 
  Das 
  

   Quadersandst. 
  oder 
  Kreidegeb. 
  in 
  Deutschland,' 
  p. 
  156; 
  1869. 
  F. 
  J. 
  Pictet 
  & 
  G. 
  

   Campiche, 
  ' 
  Foss. 
  des 
  Terr. 
  Cret. 
  de 
  Ste. 
  Croix,' 
  Mater. 
  Pal. 
  Suisse, 
  ser. 
  5, 
  pt. 
  iii. 
  

   p. 
  225, 
  pi. 
  cxv. 
  f. 
  3-5 
  ; 
  1877 
  ? 
  A. 
  Fritsch, 
  ' 
  Stud, 
  im 
  Gebiete 
  der 
  bohin. 
  Kreideformat. 
  

   II. 
  Die 
  Weissenberger 
  u. 
  Malnitzer 
  Schichten,' 
  p. 
  116, 
  f. 
  76; 
  1873. 
  H. 
  B. 
  Geinitz, 
  

   ' 
  Das 
  Elbthalgeb. 
  in 
  Sachsen,' 
  Palaeontographica, 
  vol. 
  xx. 
  pt. 
  ii. 
  p. 
  62, 
  pi. 
  xvii. 
  f. 
  14-16 
  ; 
  

   1883. 
  A. 
  Fritsch, 
  ' 
  Stud, 
  iru 
  Gebiete 
  der 
  bohin. 
  Kreideformat. 
  ILL 
  Die 
  Iserschichten,' 
  

   p. 
  100, 
  f. 
  65 
  ; 
  1895. 
  E. 
  Tiessen, 
  Zeitschr. 
  der 
  Deutsch. 
  geol. 
  Gesellsch. 
  vol. 
  xlvii. 
  p. 
  486. 
  

  

  Remarks 
  . 
  — 
  This 
  species 
  was 
  founded 
  by 
  d'Orbigny 
  on 
  casts 
  from 
  

   the 
  French 
  Cenomanian. 
  Mr. 
  Jukes-Browne 
  has 
  sent 
  me 
  specimens 
  

   from 
  the 
  Chloritic 
  Marl 
  of 
  Chard, 
  one 
  of 
  which 
  has 
  the 
  shell 
  pre- 
  

   served. 
  I 
  have 
  seen 
  only 
  four 
  specimens 
  from 
  the 
  Chalk 
  Rock 
  ; 
  one 
  

   (fig. 
  25) 
  is 
  in 
  the 
  form 
  of 
  an 
  internal 
  mould 
  of 
  both 
  valves, 
  but 
  the 
  

   others 
  have 
  a 
  considerable 
  portion 
  of 
  the 
  shell 
  present. 
  The 
  latter 
  

   agree 
  with 
  the 
  Chard 
  specimen, 
  and 
  the 
  internal 
  mould 
  is 
  like 
  

   d'Orbigny's 
  figure. 
  

  

  Affinities. 
  — 
  Geinitz 
  considers 
  that 
  d'Orbigny's 
  Cyprina 
  ligeriensis 
  

   and 
  C. 
  Noueliana 
  are 
  identical 
  with 
  this 
  species. 
  0. 
  Noueliana 
  was 
  

   founded 
  on 
  a 
  cast. 
  D'Orbigny 
  considered 
  that 
  his 
  C. 
  quadrata 
  was 
  

  

  