﻿428 
  E. 
  F. 
  TOMES 
  ON 
  IOWEE-OOLITE 
  MADEEPOEAEIA. 
  

  

  On 
  the 
  top 
  of 
  the 
  corallum 
  the 
  calices 
  are 
  crowded 
  and 
  have 
  more 
  

   or 
  less 
  of 
  an 
  angular 
  outline, 
  as 
  in 
  Isastrcea 
  ; 
  but 
  in 
  well-preserved 
  

   calices 
  the 
  septa 
  are 
  all 
  exsert, 
  and 
  a 
  narrow 
  furrow 
  invariably 
  

   indicates 
  their 
  line 
  of 
  contact 
  with 
  each 
  other. 
  In 
  younger 
  specimens 
  

   they 
  are 
  less 
  closely 
  packed 
  ; 
  and 
  then 
  they 
  preserve 
  their 
  rounded 
  

   form. 
  

  

  When 
  rubbed 
  dowu, 
  the 
  corallites 
  are 
  seen 
  to 
  be 
  distinct 
  from 
  each 
  

   other, 
  though 
  there 
  is 
  not 
  space 
  enough 
  between 
  them 
  for 
  the 
  

   growth 
  of 
  any 
  exotheca. 
  

  

  The 
  septa 
  are 
  rather 
  thick, 
  exsert, 
  and 
  have 
  their 
  margins 
  fur- 
  

   nished 
  with 
  regular 
  tubercles, 
  of 
  which 
  there 
  are 
  eight 
  or 
  nine 
  on 
  

   each 
  septum. 
  

  

  There 
  are 
  five 
  cycles 
  and 
  part 
  of 
  a 
  sixth. 
  The 
  primary 
  ones 
  are 
  

   all 
  of 
  nearly 
  uniform 
  thickness, 
  and 
  almost 
  meet 
  in 
  the 
  centre, 
  leaving 
  

   a 
  very 
  small 
  and 
  irregular 
  fossula. 
  The 
  septa 
  of 
  the 
  second 
  cycle 
  

   are 
  nearly 
  as 
  long 
  as 
  the 
  first, 
  and 
  those 
  of 
  the 
  third 
  are 
  two 
  thirds 
  

   of 
  the 
  length 
  of 
  the 
  first. 
  

  

  Diameter 
  of 
  the 
  corallites 
  about 
  2 
  lines. 
  

  

  Height 
  of 
  the 
  corallum 
  6 
  inches, 
  diameter 
  4 
  inches. 
  

  

  From 
  the 
  oolite 
  marl 
  at 
  Sheepscombe. 
  Young 
  examples 
  have 
  

   also 
  been 
  taken 
  from 
  the 
  same 
  bed 
  by 
  my 
  friend 
  Mr. 
  T. 
  J. 
  Slatter, 
  

   F. 
  G. 
  S., 
  and 
  by 
  myself 
  at 
  Leckhampton 
  Hill. 
  

  

  Genus 
  Choeisasxe^ea, 
  de 
  From. 
  

   Choeisastr^a 
  exjgosa, 
  n.sp. 
  

  

  The 
  corallum 
  springs 
  from 
  a 
  point 
  of 
  attachment, 
  and 
  is 
  at 
  first 
  

   massive 
  ; 
  but 
  the 
  corallites 
  are 
  afterwards 
  divided 
  into 
  groups 
  or 
  are 
  

   single. 
  

  

  The 
  under 
  surface 
  is 
  rugged, 
  and 
  expands 
  upwards 
  and 
  outwards, 
  

   and 
  the 
  corallites 
  show 
  in 
  has 
  relief. 
  

  

  A 
  common, 
  wrinkled 
  and 
  thick 
  epitheca 
  encloses 
  the 
  under 
  part 
  

   as 
  well 
  as 
  the 
  bundles 
  of 
  corallites 
  and 
  the 
  single 
  ones. 
  The 
  upper 
  

   or 
  calicular 
  surface 
  is 
  flat, 
  and 
  the 
  calices 
  are 
  arranged 
  a 
  good 
  deal 
  in 
  

   series. 
  Towards 
  the 
  centre 
  the 
  calices 
  are 
  most 
  crowded, 
  and 
  consti- 
  

   tute 
  oftentimes 
  a 
  confused 
  mass 
  of 
  confluent 
  calices 
  ; 
  but 
  towards 
  the 
  

   outside, 
  and 
  even 
  when 
  not 
  divided 
  either 
  into 
  single 
  calices 
  or 
  into 
  

   groups, 
  they 
  are 
  well 
  defined, 
  round 
  and 
  prominent, 
  and 
  sometimes 
  

   have 
  a 
  rudiment 
  of 
  epitheca 
  surrounding 
  them. 
  Their 
  septa 
  are 
  exsert, 
  

   rather 
  stout, 
  and 
  diminish 
  in 
  thickness 
  as 
  they 
  approach 
  the 
  centre 
  

   of 
  the 
  calice, 
  where 
  the 
  greater 
  part 
  of 
  them 
  unite 
  and 
  form 
  a 
  spurious 
  

   but 
  dense 
  columella. 
  

  

  It 
  is 
  rather 
  difficult 
  to 
  determine 
  with 
  exactness 
  the 
  number 
  of 
  

   cycles 
  ; 
  but 
  in 
  the 
  single 
  and 
  prominent 
  calices 
  there 
  are 
  about 
  120 
  

   septa, 
  or 
  five 
  cycles 
  and 
  part 
  of 
  a 
  sixth. 
  

  

  All 
  the 
  specimens 
  examined 
  have 
  lost 
  the 
  edges 
  of 
  the 
  septa 
  ; 
  but 
  

   the 
  vertical 
  ridges 
  which 
  ornament 
  their 
  sides 
  remain 
  and 
  are 
  acute, 
  

   irregular, 
  and 
  not 
  very 
  near 
  together. 
  

  

  Dessepiments 
  are 
  abundant. 
  

  

  I 
  have 
  met 
  with 
  this 
  species 
  in 
  the 
  lower 
  reef 
  only, 
  at 
  Crickley 
  Hill, 
  

  

  

  