﻿424 
  E. 
  F. 
  TOMES 
  ON 
  LOWER- 
  OOLITE 
  MADREPORARIA. 
  

  

  so 
  often 
  see 
  is 
  the 
  case 
  in 
  simple 
  Astraeidae, 
  though 
  it 
  is 
  much 
  more 
  

   rarely 
  observed 
  in 
  the 
  compound 
  species. 
  I 
  have 
  now 
  before 
  me 
  

   a 
  specimen 
  of 
  Isastrcea 
  Murckisoni^ 
  from 
  the 
  Lias 
  of 
  Skye, 
  in 
  

   which 
  the 
  inner 
  calice 
  is 
  very 
  distinct: 
  in 
  some 
  of 
  the 
  larger 
  and 
  

   older 
  calices, 
  just 
  as 
  in 
  Elysastrcea, 
  to 
  which 
  genus 
  this 
  species 
  is 
  

   closely 
  affined. 
  

  

  A 
  reference 
  to 
  the 
  figures 
  of 
  Isastrcea 
  tenuistriata 
  lately 
  published 
  

   by 
  Prof. 
  Quenstedt* 
  may 
  be 
  desirable, 
  as 
  they 
  explain 
  in 
  some 
  

   degree 
  the 
  peculiarities 
  I 
  have 
  mentioned, 
  though 
  at 
  the 
  same 
  time 
  

   they 
  seem 
  to 
  indicate 
  intercalicular 
  gemmation. 
  That 
  celebrated 
  

   palaeontologist 
  does 
  not, 
  however, 
  appear 
  to 
  have 
  regarded 
  the 
  

   species 
  as 
  possessing 
  affinity 
  with 
  Elysastrcea, 
  but. 
  associating 
  it 
  

   with 
  Isastrcea 
  helianthoides 
  and 
  Isastrcea 
  explanata, 
  considers 
  them 
  

   as 
  the 
  ultimate 
  development 
  of 
  the 
  form 
  which 
  he 
  distinguishes 
  by 
  

   the 
  name 
  of 
  CcenotJieea. 
  The 
  last-named 
  genus 
  is 
  almost 
  unknown 
  

   in 
  this 
  country 
  ; 
  and 
  I 
  am 
  unable 
  to 
  offer 
  any 
  opinion 
  on 
  the 
  

   relationship 
  here 
  suggested 
  between 
  it 
  and 
  Isastrcea, 
  excepting 
  to 
  

   remark 
  that 
  both 
  increase 
  by 
  gemmation 
  and 
  not 
  by 
  fissiparity. 
  

  

  I 
  have 
  placed 
  this 
  curious 
  species 
  in 
  the 
  genus 
  Confasastrcea 
  

   with 
  considerable 
  doubt, 
  because 
  it 
  possesses 
  some 
  peculiarities 
  

   which 
  I 
  have 
  not 
  seen 
  in 
  that 
  genus, 
  though 
  it 
  is 
  quite 
  possible 
  

   that 
  they 
  exist. 
  One 
  of 
  these 
  is 
  the 
  mode 
  of 
  gemmation, 
  which 
  

   is 
  wholly 
  external, 
  and 
  takes 
  place 
  so 
  low 
  down 
  on 
  the 
  outside 
  of 
  

   the 
  corallum 
  that 
  none 
  of 
  the 
  corallites 
  can 
  properly 
  be 
  said 
  to 
  

   be 
  furcate. 
  Another 
  is 
  the 
  great 
  distinctness 
  of 
  the 
  corallites, 
  

   notwithstanding 
  that 
  they 
  arc 
  enclosed 
  by 
  a 
  common 
  and 
  thick 
  

   epitheca 
  ; 
  and 
  another 
  the 
  distinct 
  periods 
  of 
  renewed 
  growth 
  or 
  

   rejuvenescence. 
  

  

  It 
  has 
  only 
  as 
  yet 
  been 
  found 
  in 
  the 
  lower 
  reef 
  at 
  Crickley 
  Hill. 
  

  

  Tribe 
  AsTR^ACEiE. 
  

  

  Provisionally 
  I 
  regard 
  the 
  genera 
  which 
  appear 
  in 
  the 
  following 
  

   Table 
  as 
  referable 
  to 
  the 
  tribe 
  Astraeaceae, 
  at 
  the 
  same 
  time, 
  however, 
  

   pointing 
  out 
  that 
  M. 
  de 
  Fromentel 
  has 
  elevated 
  two 
  of 
  them 
  to 
  the 
  

   rank 
  of 
  a 
  family. 
  These 
  are 
  Latimceandra 
  and 
  Chorisastrcea. 
  

  

  I 
  have 
  included 
  Isastrcea 
  in 
  the 
  classification, 
  although 
  it 
  has 
  

   not 
  serial 
  calices, 
  to 
  show 
  how 
  near 
  Latimceandra 
  comes 
  to 
  it 
  in 
  

   having 
  some 
  of 
  the 
  calices 
  single. 
  But 
  the 
  similarity 
  to 
  it 
  in 
  that 
  

   respect 
  must 
  not 
  be 
  regarded 
  as 
  of 
  much 
  importance, 
  because 
  

   gemmation 
  may 
  at 
  any 
  time 
  take 
  place 
  in 
  the 
  simple 
  calices, 
  and 
  

   they 
  may 
  become 
  serial, 
  and 
  remain 
  characteristically 
  represen- 
  

   tative 
  of 
  the 
  genus 
  Latimceandra 
  by 
  remaining 
  in 
  a 
  series. 
  

  

  Of 
  all 
  the 
  species 
  of 
  Latimceandra 
  which 
  I 
  have 
  examined, 
  

   L. 
  Davidsoni 
  and 
  L. 
  Fleminc/i 
  have 
  the 
  most 
  regularly 
  developed 
  

   inner 
  walls, 
  and 
  approach 
  most 
  nearly 
  to 
  the 
  genus 
  Isastrcea. 
  In 
  

   these 
  species, 
  when 
  gemmation 
  takes 
  place, 
  as 
  it 
  does, 
  within 
  the 
  

   calice, 
  a 
  distinct 
  wall 
  often 
  appears 
  after 
  a 
  time 
  around 
  the 
  young 
  

   corallum, 
  as 
  in 
  Isastrcea. 
  This 
  does 
  not 
  happen 
  in 
  the 
  allied 
  genus 
  

  

  * 
  Petrefact. 
  Deutschl. 
  Korallen. 
  

  

  