﻿INFERIOR 
  OOLITE 
  OF 
  SHIPTON 
  GORGE, 
  DORSET. 
  569 
  

  

  Length 
  of 
  zoarium 
  4*7 
  millim., 
  width 
  at 
  base 
  0*7 
  ; 
  zooecial 
  width 
  

   0'27 
  ; 
  aperture 
  0*1. 
  

  

  Zoarium 
  Y-shaped, 
  erect, 
  with 
  roughly 
  triangular 
  stem 
  and 
  

   branches. 
  Zooecia 
  in 
  irregular 
  transverse 
  rows 
  or 
  clusters, 
  3 
  or 
  4 
  

   on 
  each 
  of 
  the 
  two 
  front 
  angles 
  of 
  the 
  zoarium. 
  The 
  front 
  pair 
  

   form 
  a 
  kind 
  of 
  mesial 
  ridge, 
  are 
  mammiform, 
  larger, 
  and 
  have 
  larger 
  

   apertures, 
  which 
  are 
  placed 
  obliquely 
  so 
  as 
  to 
  appear 
  alternating. 
  

   Outermost 
  zooecia 
  pentagonal 
  with 
  small 
  apertures, 
  the 
  two 
  next 
  are 
  

   less 
  distinctly 
  pentagonal. 
  The 
  ornamental 
  areolation 
  of 
  the 
  dorsal 
  

   surface 
  is 
  given 
  by 
  the 
  pentagonal 
  walls 
  of 
  the 
  blind 
  cells. 
  Aperture 
  

   orbicular, 
  with 
  a 
  calcareous 
  centrally 
  perforate 
  closure 
  within 
  the 
  

   mouth. 
  Surface 
  punctate. 
  Ovicells 
  pyriform 
  inflations 
  involving 
  

   two 
  or 
  more 
  zooecial 
  tubes, 
  or 
  pyriform 
  sacs 
  disposed 
  on 
  the 
  front 
  of 
  

   the 
  branches. 
  

  

  Though 
  the 
  specimens 
  are 
  all 
  Y-shaped, 
  there 
  is 
  evidence 
  of 
  other 
  

   branches 
  being 
  thrown 
  out. 
  It 
  may 
  be 
  regarded 
  as 
  an 
  erect 
  variety 
  

   of 
  Idmonea 
  triquetra, 
  Lamx., 
  differing 
  also 
  in 
  having 
  fewer 
  developed 
  

   cells 
  in 
  each 
  row. 
  

  

  Another 
  diverging 
  form 
  commences 
  growth 
  with 
  four 
  cells 
  placed 
  

   transversely 
  but 
  opening 
  at 
  irregular 
  intervals. 
  The 
  developed 
  zooecia 
  

   subsequently 
  increase 
  to 
  six, 
  with 
  the 
  middle 
  pair 
  but 
  very 
  little 
  

   elevated 
  above 
  those 
  on 
  the 
  sides. 
  Surface, 
  aperture, 
  and 
  closure 
  

   the 
  same 
  as 
  in 
  the 
  type. 
  

  

  Idmonea 
  triquetra, 
  Lamx., 
  var. 
  Parkinsoni, 
  nov. 
  (PI. 
  XYIII. 
  

   ng. 
  13.) 
  

  

  Lateral 
  width 
  of 
  zoarium 
  09 
  millim., 
  thickness 
  0*6 
  ; 
  mesial 
  aper- 
  

   tures 
  0*1. 
  

  

  Zoarium 
  erect, 
  ovately 
  triangular, 
  and 
  slightly 
  claviform. 
  Base 
  

   of 
  stem 
  at 
  point 
  of 
  attachment 
  narrow, 
  rapidly 
  increasing 
  to 
  normal 
  

   width, 
  and 
  becoming 
  somewhat 
  sinuous 
  in 
  its 
  course 
  of 
  growth. 
  

   Zooecia 
  in 
  the 
  poriferous 
  area, 
  three 
  on 
  each 
  side, 
  rarely 
  four, 
  ar- 
  

   ranged 
  in 
  transverse 
  rows, 
  with 
  thick 
  walls 
  rising 
  above 
  the 
  zooecial 
  

   surface. 
  The 
  two 
  front 
  zooecia 
  are 
  larger, 
  mammiform, 
  and 
  divergent. 
  

   Non-poriferous 
  area 
  rounded, 
  ornamented 
  with 
  the 
  hexagonal 
  or 
  

   pentagonal 
  walls 
  of 
  the 
  blind 
  cells. 
  Apertures 
  oval. 
  Surface 
  

   punctulate 
  with 
  terminal 
  papillae. 
  Ovicells 
  irregular 
  globose 
  swel- 
  

   lings 
  enveloping 
  two 
  or 
  three 
  zooecia, 
  and 
  placed 
  ordinarily 
  in 
  front 
  

   of 
  the 
  zoarium. 
  

  

  3. 
  Idmonea 
  claviformis, 
  sp. 
  nov. 
  (PL 
  XIX. 
  figs. 
  1, 
  2.) 
  

  

  Zoarial 
  length 
  5'0 
  millim., 
  zoarial 
  lateral 
  width 
  L3; 
  apertures, 
  

   perfect 
  0*03, 
  worn 
  0-1. 
  

  

  Zoarium 
  erect, 
  clavate, 
  ovately 
  triangular 
  with 
  flattened 
  sides, 
  

   ordinarily 
  curving 
  backwards 
  from 
  above 
  the 
  middle. 
  Zooecia 
  in 
  

   curved 
  alternate 
  rows, 
  five 
  or 
  six 
  peristomes 
  in 
  each 
  row 
  on 
  the 
  

   poriferous 
  sides 
  of 
  the 
  zoarium, 
  the 
  median 
  pair 
  teat-like 
  and 
  

   forming 
  a 
  pseudo-carina. 
  The 
  width 
  of 
  the 
  non-poriferous 
  dorsal 
  

   area 
  is 
  two 
  thirds 
  only 
  of 
  the 
  breadth 
  of 
  the 
  sides. 
  Ovicells 
  irregular 
  

  

  Q.J.G.S. 
  No. 
  179. 
  2 
  s 
  

  

  