﻿R. 
  F. 
  TOMES 
  ON 
  LOWER-OOLITE 
  MADREPORARIA. 
  431 
  

  

  inwards 
  of 
  this 
  outer 
  wall, 
  and 
  not 
  by 
  the 
  growth 
  of 
  inner 
  walls, 
  

   as 
  in 
  Isastrcea 
  and 
  Latimceandra, 
  that 
  the 
  sinuous 
  ridges 
  are 
  formed. 
  

   It 
  is 
  with 
  Latimceandra 
  rather 
  than 
  with 
  Heterogyra 
  that 
  this 
  genus 
  

   is 
  by 
  its 
  mode 
  of 
  gemmation 
  most 
  nearly 
  associated 
  ; 
  but 
  there 
  are 
  no 
  

   true 
  walls 
  as 
  in 
  Latimceandra 
  either 
  dividing 
  the 
  calices 
  into 
  short 
  

   series 
  or 
  enclosing 
  single 
  ones. 
  Moreover 
  the 
  elongated 
  septa 
  of 
  

   Phyllogyra 
  are 
  true 
  costse 
  ; 
  and 
  none 
  such 
  occur 
  within 
  the 
  well- 
  

   developed 
  walls 
  of 
  Latimceandra. 
  

  

  Phyllogyra 
  Etheridgei, 
  Dune. 
  sp. 
  

  

  Symphyllia 
  Etheridgei, 
  Duncan, 
  Suppl. 
  Brit. 
  Foss. 
  Cor. 
  pt. 
  iii. 
  

   p. 
  19, 
  pi. 
  vi. 
  figs. 
  5-8. 
  

  

  This 
  species 
  has 
  been 
  met 
  with 
  quite 
  commonly 
  in 
  the 
  Trigonia- 
  

   grit 
  at 
  Leckhampton 
  ; 
  and 
  I 
  have 
  a 
  single 
  specimen 
  which 
  was 
  ob- 
  

   tained 
  somewhere 
  near 
  Cooper's 
  Hill 
  by 
  my 
  late 
  friend 
  Mr. 
  J. 
  W. 
  

   Kirshaw, 
  F.G.S. 
  ; 
  but 
  from 
  no 
  other 
  locality 
  have 
  I 
  as 
  yet 
  met 
  with 
  

   it. 
  It 
  appears 
  to 
  be 
  wholly 
  confined 
  to 
  the 
  upper 
  reef 
  of 
  Dr. 
  

   Wright 
  ; 
  and 
  the 
  Leckhampton 
  specimens 
  occur, 
  for 
  the 
  most 
  part, 
  

   quite 
  at 
  the 
  bottom 
  of 
  the 
  bed 
  which 
  takes 
  its 
  name 
  from 
  the 
  Tri- 
  

   gonia 
  costata. 
  

  

  A 
  specimen 
  in 
  Dr. 
  Wright's 
  collection 
  has 
  been 
  named 
  by 
  Prof. 
  

   Duncan 
  ; 
  and 
  an 
  examination 
  of 
  it, 
  with 
  the 
  opportunity 
  of 
  com- 
  

   paring 
  numerous 
  and 
  more 
  characteristic 
  specimens, 
  has 
  enabled 
  

   me 
  to 
  determine 
  its 
  true 
  character 
  with 
  tolerable 
  certainty. 
  The 
  

   Coopers-hill 
  example 
  shows 
  gemmation 
  actively 
  taking 
  place 
  at 
  the 
  

   margin 
  of 
  the 
  leaf-like 
  expansion. 
  

  

  Phyllogyra 
  sinuosa, 
  n. 
  sp. 
  (PI. 
  XVIIL 
  figs. 
  5-7.) 
  

  

  The 
  corallum 
  is 
  of 
  rather 
  small 
  size 
  and 
  depressed, 
  the 
  under 
  

   surface 
  being 
  either 
  flattened 
  or 
  concave 
  ; 
  and 
  there 
  is 
  no 
  appear- 
  

   ance 
  of 
  a 
  peduncle. 
  The 
  upper 
  surface 
  is 
  either 
  flat 
  or 
  convex. 
  

  

  The 
  furrows 
  are 
  sometimes 
  long 
  and 
  rather 
  deep, 
  and 
  they 
  are 
  

   nearly 
  as 
  wide 
  at 
  the 
  bottom 
  as 
  at 
  the 
  top. 
  They 
  are 
  very 
  tortuous, 
  

   of 
  very 
  unequal 
  breadth 
  ; 
  and 
  the 
  ridges 
  bounding 
  them 
  are 
  conse- 
  

   quently 
  very 
  sinuous. 
  These 
  furrows, 
  with 
  their 
  surrounding 
  

   ridges, 
  are 
  in 
  fact 
  long 
  unsymmetrical 
  leaves, 
  often 
  having 
  lobes, 
  

   the 
  edges 
  of 
  which 
  are 
  turned 
  up 
  all 
  round 
  and 
  rise 
  up 
  into 
  a 
  

   kind 
  of 
  peak, 
  where 
  they 
  meet 
  and 
  make 
  angles. 
  At 
  no 
  point 
  do 
  

   these 
  ridges 
  present 
  the 
  appearance 
  of 
  true 
  walls, 
  as 
  in 
  Latimce- 
  

   andra 
  Davidsoni 
  and 
  L. 
  Flemingi. 
  Not 
  more 
  than 
  six 
  calices 
  occur 
  

   in 
  one 
  leaf 
  or 
  furrow. 
  They 
  are 
  small, 
  rather 
  deep, 
  pretty 
  well 
  

   defined, 
  and 
  not 
  very 
  closely 
  placed. 
  

  

  The 
  septa 
  are 
  thin, 
  flexuous, 
  equal 
  in 
  thickness 
  throughout 
  ; 
  and 
  

   the 
  principal 
  ones 
  pass 
  quite 
  into 
  the 
  centre 
  of 
  the 
  fossula, 
  but 
  do 
  not 
  

   there 
  form 
  a 
  mass. 
  Their 
  edges 
  are 
  delicately 
  papillated. 
  They 
  

   frequently 
  anastomose, 
  but 
  only 
  near 
  the 
  outside 
  of 
  the 
  leaf, 
  where 
  

   they 
  must 
  be 
  regarded 
  as 
  septal 
  costae 
  rather 
  than 
  as 
  septa. 
  There 
  

   are 
  about 
  twenty-four 
  septa 
  to 
  each 
  calice. 
  

  

  Gemmation 
  takes 
  place 
  near 
  to 
  the 
  margin 
  of 
  the 
  leaf, 
  and 
  

   more 
  frequently 
  on 
  the 
  side 
  of 
  the 
  corallum 
  than 
  on 
  the 
  top 
  — 
  that 
  is 
  

  

  