﻿430 
  R. 
  E. 
  TOMES 
  ON 
  LOWER-OOLITE 
  MADREPORARIA. 
  

  

  depressed 
  Montlivaltia, 
  attached 
  by 
  its 
  whole 
  breadth 
  ; 
  and 
  the 
  first 
  

   indication 
  of 
  a 
  deviation 
  from 
  that 
  form 
  appears 
  by 
  the 
  outer 
  mar- 
  

   gin 
  assuming 
  greater 
  lateral 
  prominence, 
  and 
  becoming 
  somewhat 
  

   lobate. 
  "With 
  continued 
  growth 
  the 
  lobes 
  become 
  more 
  distinct, 
  

   until 
  their 
  sides 
  meet 
  and 
  push 
  each 
  other 
  upwards 
  into 
  short 
  

   subcristiform 
  ridges. 
  About 
  this 
  time 
  gemmation 
  first 
  makes 
  its 
  

   appearance 
  amongst 
  the 
  elongated 
  septa 
  (costse) 
  near 
  the 
  extremity 
  

   of 
  the 
  lobes, 
  sometimes 
  in 
  each 
  one 
  simultaneously, 
  and 
  producing 
  

   a 
  complete 
  circle 
  of 
  young 
  calices 
  around 
  the 
  parent 
  one 
  ; 
  though 
  

   more 
  frequently 
  they 
  are 
  few 
  in 
  number, 
  and 
  irregular 
  both 
  as 
  to 
  

   position 
  and 
  time 
  of 
  making 
  their 
  appearance. 
  

  

  Although 
  I 
  have 
  examined 
  great 
  numbers 
  of 
  this 
  coral,. 
  I 
  have 
  

   hitherto 
  wholly 
  failed 
  to 
  detect 
  gemmation 
  taking 
  place 
  after 
  the 
  

   formation 
  of 
  the 
  basal 
  portion 
  of 
  the 
  corallum 
  ; 
  and 
  if 
  it 
  is 
  confined 
  

   to 
  that 
  part, 
  this 
  species 
  would 
  resemble 
  Ghorisastrcea 
  in 
  its 
  mode 
  of 
  

   development. 
  

  

  The 
  corallitcs 
  which 
  have 
  more 
  than 
  one 
  calice, 
  have 
  often 
  much 
  

   the 
  appearance 
  of 
  fissiparous 
  growth; 
  but 
  a 
  close 
  examination 
  

   shows 
  that 
  the 
  calices 
  are 
  tberesult 
  of 
  gemmation 
  which 
  took 
  place 
  lower 
  

   down 
  in 
  the 
  corallum, 
  and 
  that 
  they 
  have 
  continued 
  their 
  near 
  re- 
  

   lationship 
  to 
  each 
  other 
  while 
  the 
  coral 
  was 
  increasing 
  in 
  height. 
  This 
  

   I 
  have 
  ascertained 
  by 
  means 
  of 
  sections, 
  showing 
  that 
  very 
  frequently 
  

   two 
  or 
  more 
  calices 
  hold 
  precisely 
  the 
  same 
  position 
  in 
  relation 
  to 
  each 
  

   other 
  on 
  the 
  summit 
  of 
  a 
  corallite 
  that 
  they 
  did 
  near 
  to 
  its 
  junction 
  

   with 
  the 
  peduncle 
  from 
  which 
  it 
  and 
  other 
  corallitcs 
  sprung. 
  

  

  I 
  have 
  arrived 
  at 
  the 
  conclusion 
  that 
  the 
  serial 
  arrangements 
  of 
  

   the 
  calices 
  in 
  the 
  group 
  to 
  which 
  this 
  species 
  belongs, 
  must 
  be 
  re- 
  

   garded 
  as 
  an 
  ultimate 
  and 
  essential 
  character, 
  and 
  not 
  as 
  representing 
  

   fissiparity 
  in 
  the 
  process 
  of 
  dividing 
  the 
  calices 
  into 
  series, 
  to 
  be 
  again 
  

   brought 
  into 
  corallites 
  with 
  simple 
  calices 
  by 
  the 
  mere 
  process 
  of 
  

   upward 
  growth. 
  

  

  Phyllogyra, 
  n. 
  g. 
  

  

  The 
  corallum 
  has 
  a 
  more 
  or 
  less 
  depressed 
  and 
  massive 
  form, 
  and 
  

   is 
  composed 
  of 
  a 
  series 
  of 
  leaf-like 
  expansions, 
  proceeding 
  laterally 
  

   from 
  a 
  parent 
  corallite, 
  the 
  curled-up 
  margins 
  of 
  which 
  unite 
  and 
  

   form 
  sinuous 
  cristiform 
  ridges, 
  the 
  line 
  of 
  union 
  of 
  which 
  is 
  very 
  

   distinct 
  in 
  the 
  younger 
  examples, 
  but 
  much 
  less 
  so 
  in 
  the 
  older 
  

   ones. 
  

  

  Gemmations 
  take 
  place 
  successively 
  amongst 
  the 
  elongated 
  septa 
  

   (which 
  must 
  be 
  regarded 
  as 
  costse 
  rather 
  than 
  septa), 
  and 
  generally 
  

   towards 
  the 
  extremity 
  of 
  the 
  leaf, 
  and 
  a 
  more 
  or 
  less 
  distinct 
  line 
  

   of 
  calices 
  is 
  produced. 
  

  

  There 
  appears 
  to 
  be 
  no 
  intercalicular 
  gemmation, 
  so 
  common 
  in 
  

   many 
  of 
  the 
  Astraeidae, 
  as, 
  for 
  instance, 
  in 
  Isastrcea 
  or 
  even 
  in 
  

   Latimceandra 
  ; 
  and 
  when 
  lateral 
  gemmation 
  has 
  ceased, 
  the 
  corallum 
  

   only 
  increases 
  in 
  height 
  by 
  the 
  growth 
  of 
  the 
  single 
  or 
  serial 
  coral- 
  

   lites 
  upwards. 
  

  

  There 
  is 
  a 
  common 
  or 
  basal 
  wall, 
  which 
  is 
  either 
  naked 
  or 
  costu- 
  

   late, 
  or 
  has 
  bands 
  of 
  rudimentary 
  epitheca. 
  It 
  is 
  by 
  the 
  folding 
  

  

  