﻿Yol. 
  53.] 
  THE 
  CRETACEOUS 
  STRATA 
  OF 
  COL'NTT 
  ANTRIM. 
  

  

  589 
  

  

  These 
  organisms, 
  however, 
  seemingly 
  disappeared 
  before 
  the 
  

   lithological 
  conditions 
  had 
  undergone 
  compete 
  change, 
  and 
  in 
  the 
  

   Glauconitic 
  Claris 
  abore 
  a 
  new 
  fauna 
  poor 
  in 
  species 
  takes 
  their 
  place. 
  

   Vermiculcmce 
  (V. 
  quinqueearinata, 
  Bom., 
  and 
  V. 
  concava, 
  Sow.) 
  

   are 
  abundant, 
  and 
  large 
  pectens 
  are 
  occasionally 
  present, 
  but 
  these 
  

   are 
  not 
  sufficient 
  to 
  determine 
  the 
  exact 
  stratigraphical 
  position 
  of 
  

   the 
  marls. 
  The 
  evidence 
  afforded 
  by 
  the 
  chemical 
  examinations 
  

   tends 
  to 
  show 
  that 
  a 
  depression 
  was 
  taking 
  place, 
  and 
  the 
  con- 
  

   tinental 
  slopes 
  were 
  being 
  denuded, 
  heavy 
  minerals 
  being 
  more 
  

   abundant, 
  and 
  the 
  calcareous 
  element 
  very 
  pronounced. 
  The 
  

   depression 
  continuing, 
  fine 
  sands 
  replace 
  the 
  clays, 
  and 
  the 
  great 
  

   series 
  of 
  the 
  Calcareous 
  or 
  Yellow 
  Sandstones 
  is 
  deposited. 
  

  

  Yellow 
  Sandstones 
  (Zone 
  of 
  Ostrea 
  carinata). 
  

  

  These 
  beds 
  have 
  practically 
  the 
  same 
  extension 
  as 
  the 
  Glauconitic 
  

   Sands, 
  but 
  have 
  not 
  hitherto 
  been 
  recorded 
  from 
  the 
  Xorthern 
  

   Division. 
  They 
  attain 
  their 
  maximum 
  thickness 
  of 
  30 
  feet 
  in 
  

   Colin 
  Glen, 
  varying 
  in 
  the 
  other 
  localities 
  examined 
  from 
  4 
  to 
  20 
  feet 
  

   in 
  thickness. 
  These 
  strata 
  are 
  very 
  uniform 
  in 
  lithological 
  character, 
  

   being 
  mainly 
  composed 
  of 
  extremely 
  minute 
  arenaceous 
  grains, 
  though 
  

   in 
  the 
  Eastern 
  Division 
  a 
  clayey 
  admixture 
  is 
  noticeable, 
  and 
  glauco- 
  

   nite 
  is 
  present 
  in 
  minute 
  particles. 
  Organic 
  contents 
  are, 
  as 
  a 
  rule, 
  

   rare, 
  but 
  they 
  are 
  more 
  abundant 
  in 
  the 
  Eastern 
  Division, 
  the 
  corals 
  and 
  

   sea-urchins 
  recorded 
  from 
  this 
  horizon 
  having 
  been 
  collected 
  chiefly 
  

   in 
  the 
  Islandmagee 
  localities. 
  The 
  distribution 
  and 
  nature 
  of 
  the 
  

   species 
  present 
  are 
  as 
  follows 
  : 
  — 
  

  

  Class. 
  

  

  Cexteal 
  Division. 
  

  

  Eastebx 
  Division. 
  

  

  Cephalopoda 
  

  

  

  Ammonites 
  [Acanthoceras] 
  

   rotomagensis 
  (in 
  museum), 
  

  

  

  

  Pelecypoda 
  : 
  

  

  

  Defr., 
  sp. 
  

  

  Dimyaria 
  

  

  Trigonia 
  scabricula, 
  Lye. 
  

   Avicula 
  sp., 
  Pinna 
  sp. 
  

  

  Area 
  sp., 
  Mytilus 
  sp. 
  

   Avicula, 
  sp. 
  

  

  

  

  Panopcea 
  mandihula, 
  Sow. 
  

  

  

  

  Cucullcea 
  ligeriensis, 
  d'Orb., 
  

  

  

  

  sp. 
  (Tate), 
  in 
  upper 
  part. 
  

  

  

  Monomyaria 
  

  

  Pecten 
  \Janira~] 
  quadricos- 
  

   tatus 
  (Sow.), 
  lower 
  part. 
  

  

  Janira 
  quadricostata 
  (Sow.). 
  

  

  

  Pecten 
  \J.~\ 
  quinquecostatus. 
  

  

  Ostrea 
  canaliculata, 
  Sow. 
  

  

  

  Sow., 
  & 
  J. 
  cequicostata, 
  

  

  Plicatula 
  infiata, 
  Sow. 
  

  

  

  Lam. 
  (in 
  upper 
  part). 
  

  

  

  

  Ostrea 
  \Alectryonia~] 
  cari- 
  

  

  

  

  nata, 
  Lain, 
  (large). 
  

  

  

  

  Lima 
  semisrdcata, 
  d'Orb., 
  & 
  

  

  

  

  L.globata,Sow. 
  (abundant). 
  

  

  

  Beachiopoda 
  

  

  Phynchonella 
  dimidiata, 
  var. 
  

  

  BhyncJwnella 
  dimidiata, 
  var. 
  

  

  

  convexa, 
  Sow. 
  

  

  convexa, 
  Sow. 
  

  

  Vebmes 
  

  

  Vermicidaria 
  quinqueeari- 
  

   nata, 
  Rom., 
  & 
  V. 
  concava, 
  

  

  Ditrupa 
  dijformis, 
  Lam. 
  

   Vermicularia 
  quinqueeari- 
  

  

  

  

  Sow. 
  

  

  nata, 
  Rom., 
  & 
  V. 
  concava, 
  

   Sow. 
  

  

  ECHIXODEEMATA... 
  

   ACTIXOZOA 
  

  

  

  Discoidea 
  subucula, 
  Klein. 
  

   Ilicrabacia 
  coronula, 
  Goldf. 
  

  

  

  

  

  