﻿R. 
  P. 
  TOMES 
  Otf 
  LOWER-OOLITE 
  MADREFORARIA. 
  423 
  

  

  CoKFLSASTRuEA. 
  TESTUISTRJATA, 
  n. 
  Sp. 
  (PI. 
  XVIII. 
  fig. 
  11.) 
  

  

  The 
  supposition 
  expressed 
  by 
  me 
  that 
  the 
  Isastrcea 
  tenuistriata 
  

   was 
  not 
  a 
  true 
  Isastrcea 
  has 
  had 
  partial 
  confirmation 
  by 
  the 
  ex- 
  

   amination 
  of 
  a 
  considerable 
  number 
  of 
  specimens, 
  which 
  show 
  that 
  

   two 
  species 
  have 
  been 
  confounded 
  under 
  that 
  name. 
  

  

  The 
  original 
  description 
  by 
  It'Coy, 
  as 
  well 
  as 
  that 
  afterwards 
  

   given 
  by 
  1D1. 
  Edwards 
  and 
  Saime. 
  will 
  apply 
  to 
  one 
  of 
  these, 
  

   which 
  is 
  a 
  true 
  Isastrcea, 
  though 
  probably 
  not 
  a 
  very 
  typical 
  species. 
  

  

  The 
  other 
  is 
  a 
  species 
  of 
  Confusastrcea, 
  and 
  may 
  be 
  described 
  as 
  

   follows 
  : 
  — 
  

  

  The 
  corallum 
  is 
  depressed 
  and 
  of 
  a 
  rounded 
  or 
  ovoid 
  form. 
  The 
  

   under 
  surface 
  is 
  a 
  little 
  convex, 
  and 
  is 
  enclosed 
  in 
  a 
  common 
  wall 
  

   and 
  epitheca, 
  notwithstanding 
  which, 
  however, 
  the 
  outline 
  of 
  each 
  

   corallite, 
  both 
  inferiorly 
  and 
  laterally, 
  is 
  well 
  defined. 
  Laterally 
  

   they 
  are 
  so 
  distinct 
  that 
  they 
  give 
  to 
  the 
  corallum 
  the 
  appearance 
  

   of 
  a 
  bundle 
  of 
  short 
  sticks 
  in 
  close 
  approximation, 
  and 
  there 
  is 
  no 
  

   appearance 
  of 
  any 
  ramification 
  of 
  the 
  corallites 
  by 
  either 
  lateral 
  

   gemmation 
  or 
  fissiparity. 
  

  

  The 
  calices 
  are 
  either 
  round 
  or 
  oval, 
  or, 
  when 
  pressed 
  together, 
  

   lozenge-shaped. 
  They 
  are 
  concave, 
  with 
  a 
  small, 
  ovoid, 
  deep, 
  and 
  

   well-defined 
  fossula, 
  and 
  the 
  septa 
  are 
  exsert 
  only 
  near 
  the 
  outside 
  

   of 
  the 
  calice. 
  Between 
  the 
  calices 
  is 
  a 
  very 
  distinct 
  though 
  narrow 
  

   line 
  of 
  depression. 
  

  

  The 
  septa 
  are 
  thin, 
  and 
  less 
  closely 
  placed 
  than 
  in 
  Isastrcea 
  tenui- 
  

   striata, 
  the 
  interceptal 
  loculi 
  being 
  of 
  a 
  breadth 
  quite 
  equal 
  to 
  three 
  

   times 
  that 
  of 
  the 
  septa. 
  The 
  number 
  of 
  septa 
  in 
  a 
  well-developed 
  

   calice 
  is 
  nearly 
  ninety 
  ; 
  that 
  is, 
  there 
  are 
  fuur 
  complete 
  cycles, 
  and 
  a 
  

   fifth 
  which 
  is 
  not 
  complete. 
  The 
  septa 
  forming 
  the 
  first, 
  second, 
  and 
  

   third 
  cycles 
  extend 
  to 
  the 
  centre, 
  and 
  pass 
  into 
  the 
  fossula 
  : 
  those 
  

   of 
  the 
  fourth 
  are 
  half 
  the 
  length 
  of 
  the 
  others, 
  and 
  those 
  of 
  the 
  

   fifth 
  are 
  rudimentary. 
  All 
  are 
  evenly 
  and 
  delicately 
  but 
  very 
  

   distinctly 
  geniculated. 
  

  

  Some 
  of 
  the 
  outer 
  and 
  half-enclosed 
  corallites 
  have 
  a 
  peculiarity 
  

   which 
  is 
  deserving 
  of 
  notice, 
  and 
  which 
  I 
  have 
  observed 
  in 
  some 
  of 
  

   the 
  Liassic 
  Isastrcece, 
  though 
  I 
  have 
  not 
  before 
  seen 
  it 
  in 
  any 
  of 
  the 
  

   massive 
  Oolitic 
  Astrgeidse. 
  I 
  refer 
  to 
  the 
  apparently 
  intermittent 
  

   growth 
  of 
  the 
  individual 
  corallites, 
  which 
  have 
  somewhat 
  the 
  

   appearance 
  of 
  those 
  of 
  some 
  of 
  the 
  Rugosa. 
  They 
  do 
  not, 
  however, 
  

   possess 
  a 
  true 
  Hugose 
  character, 
  though 
  they 
  probably 
  approximate 
  

   the 
  species 
  to 
  the 
  Triassic 
  genus 
  Elysastrcea 
  of 
  Laube 
  *, 
  from 
  which, 
  

   however, 
  it 
  differs 
  in 
  having 
  a 
  well-developed 
  epitheca, 
  and 
  gem- 
  

   mation 
  which 
  is 
  confined 
  to 
  the 
  circumference 
  of 
  the 
  corallum 
  f 
  . 
  

  

  The 
  inner 
  ring 
  of 
  septa 
  in 
  Elysastrcea, 
  as 
  shown 
  in 
  Laube's 
  figure 
  

   and 
  in 
  the 
  figures 
  given 
  by 
  Prof. 
  Duncan 
  $, 
  appears 
  to 
  me 
  to 
  be 
  due 
  

   only 
  to 
  this 
  rejuvenescence 
  of 
  the 
  corallites. 
  It 
  is 
  merely 
  a 
  new 
  

   calice 
  arising 
  from 
  the 
  centre 
  of 
  an 
  older 
  and 
  larger 
  one, 
  just 
  as 
  we 
  

  

  * 
  Die 
  Fauna 
  der 
  Schickten 
  von 
  St. 
  Cassian, 
  p. 
  261, 
  pi. 
  v. 
  fig. 
  6 
  (1864). 
  

   t 
  Indicating, 
  perhaps, 
  some 
  affinity 
  with 
  the 
  group 
  containing 
  Lati 
  mceancl 
  ra 
  , 
  

   Chorisastrcsa, 
  and 
  Pky/Ioyyra. 
  

   \ 
  Supp. 
  Brit. 
  Foss. 
  Cor. 
  

  

  