﻿438 
  R. 
  F. 
  TOMES 
  OX 
  LOWER-OOLITE 
  MADREPOKARIA. 
  

  

  surface 
  ; 
  but 
  towards 
  the 
  outside 
  there 
  is 
  ofteu 
  a 
  disposition 
  towards 
  

   a 
  linear 
  arrangement, 
  the 
  lines 
  corresponding 
  with 
  the 
  outer 
  margin. 
  

   The}' 
  are 
  distant 
  from 
  each 
  other 
  in 
  every 
  direction 
  about 
  1^ 
  line. 
  

  

  The 
  septa 
  and 
  septal 
  costae 
  are 
  thin, 
  and 
  they 
  are 
  irregular 
  both 
  in 
  

   their 
  length 
  and 
  degree 
  of 
  prominence. 
  They 
  are 
  crooked, 
  but 
  not 
  

   by 
  a 
  curvature, 
  but 
  by 
  having 
  from 
  two 
  to 
  four 
  angles 
  between 
  one 
  

   calice 
  and 
  another. 
  The 
  principal 
  ones 
  are 
  much 
  more 
  prominent 
  

   than 
  the 
  others 
  ; 
  but 
  their 
  degree 
  of 
  projection 
  is 
  irregular. 
  All, 
  

   when 
  unworn, 
  have 
  thin 
  edges, 
  which 
  have 
  rather 
  obscure 
  pro- 
  

   cesses, 
  which 
  are 
  long 
  in 
  the 
  direction 
  of 
  the 
  length 
  of 
  the 
  septum. 
  

   There 
  is 
  a 
  slight 
  tendency 
  in 
  the 
  septal 
  costae 
  towards 
  a 
  radiate 
  

   arrangement 
  ; 
  but 
  this 
  is 
  very 
  little 
  observable 
  in 
  many 
  specimens. 
  

   They 
  very 
  rarely 
  anastomose 
  with 
  each 
  other. 
  

  

  The 
  greater 
  prominence 
  of 
  the 
  principal 
  septa 
  and 
  septal 
  costae, 
  

   their 
  thinness 
  when 
  unworn, 
  as 
  well 
  as 
  their 
  angular 
  but 
  not 
  

   curved 
  form, 
  will 
  distinguish 
  this 
  species 
  from 
  others 
  from 
  the 
  

   Inferior 
  Oolite. 
  

  

  \Vlien 
  worn 
  down 
  the 
  septal 
  costae 
  have 
  great 
  irregularity, 
  each 
  

   in 
  its 
  own 
  length 
  : 
  but 
  they 
  do 
  not 
  much 
  differ 
  from 
  each 
  other. 
  

   The 
  largest 
  specimen 
  I 
  have 
  seen 
  is 
  5 
  inches 
  in 
  diameter, 
  and 
  1| 
  

   inch 
  thick. 
  

  

  It 
  occurs 
  plentifully 
  in 
  the 
  Tru/onia-grit 
  of 
  Ravcnsgate 
  Hill, 
  

   Brown's 
  Hill, 
  Birdlip-Hill, 
  and 
  a 
  railway-cutting 
  between 
  Bourton- 
  

   on-the-Watcr 
  and 
  Notgrove, 
  and 
  also 
  in 
  the 
  Perna-bed 
  at 
  Cold 
  

   Comfort, 
  near 
  Cheltenham. 
  

  

  TnAMNASTR^EA 
  FLABELLIFORMIS, 
  n. 
  Sp. 
  

  

  Three 
  instances 
  only 
  of 
  the 
  occurrence 
  of 
  this 
  species, 
  which 
  is 
  

   distinct 
  from 
  all 
  others 
  I 
  bave 
  seen, 
  are 
  known 
  to 
  me. 
  

  

  The 
  corallum 
  of 
  one 
  of 
  the 
  specimens 
  is 
  attached, 
  and 
  consists 
  of 
  

   three 
  upright 
  turbinate 
  parts, 
  united 
  into 
  a 
  series, 
  and 
  forming 
  a 
  fla- 
  

   belliform 
  figure, 
  surrounded 
  by 
  a 
  common 
  epitheca, 
  and 
  having 
  a 
  flat- 
  

   tened 
  top, 
  which 
  constitutes 
  the 
  calicular 
  surface. 
  This 
  is 
  concave 
  

   across 
  its 
  narrow 
  diameter, 
  and 
  convex 
  along 
  its 
  long 
  diameter. 
  

  

  The 
  epitheca 
  is 
  thick, 
  not 
  very 
  rugose, 
  and 
  has 
  shallow 
  concentric 
  

   markings. 
  It 
  extends 
  up 
  to 
  the 
  edge 
  of 
  the 
  calicular 
  surface. 
  

  

  Towards 
  the 
  foot 
  of 
  the 
  corallum 
  the 
  mural 
  costae 
  are 
  partially 
  

   exposed, 
  and 
  are 
  numerous, 
  delicate, 
  straight, 
  and 
  have 
  thickly 
  set 
  

   delicate 
  cuneiform 
  synapticulae. 
  

  

  The 
  calicular 
  surface 
  has 
  an 
  irregular 
  elongated 
  flattened 
  form, 
  

   with 
  a 
  lateral 
  lobular 
  outline 
  ; 
  and 
  the 
  calices 
  are 
  arranged 
  in 
  lines 
  

   corresponding 
  with 
  the 
  outer 
  or 
  longer 
  boundary, 
  and 
  follow 
  its 
  

   lobular 
  outline. 
  There 
  are 
  three 
  lines 
  ; 
  but 
  the 
  middle 
  one 
  is 
  very 
  

   irregular. 
  They 
  are 
  rather 
  deep 
  ; 
  and 
  the 
  septal 
  costae 
  passing 
  over 
  

   the 
  ridges 
  between 
  the 
  lines 
  give 
  them 
  a 
  subcristiform 
  aspect, 
  some- 
  

   what 
  as 
  in 
  Oroseris 
  and 
  Dimorphastrcea. 
  The 
  septa 
  and 
  the 
  septal 
  

   costae 
  are 
  regular, 
  very 
  delicate, 
  and 
  moniliform. 
  There 
  are 
  three 
  

   cycles 
  of 
  septa. 
  

  

  Height 
  of 
  the 
  corallum 
  10 
  lines. 
  Longest 
  diameter 
  of 
  the 
  calicular 
  

  

  