﻿Report 
  of 
  the 
  State 
  Geologist. 
  

  

  889 
  

  

  In 
  fig. 
  30 
  the 
  connecting 
  processes 
  are 
  not 
  opposite 
  to 
  each 
  

   other 
  as 
  in 
  fig. 
  29, 
  bnt 
  alternating, 
  meeting 
  midway 
  between 
  the 
  

   adjacent 
  branches, 
  coalescing, 
  forming 
  a 
  secondary 
  ridge 
  or 
  

   pseudo-carina, 
  giving 
  the 
  typical 
  form 
  of 
  Ilemitrypa 
  of 
  Phillips. 
  

  

  From 
  iig. 
  29, 
  Unitrypa, 
  there 
  is 
  a 
  departure 
  in 
  another 
  direction 
  

   and 
  a 
  gradual 
  change 
  to 
  Loculipora. 
  

  

  In 
  fig. 
  31 
  the 
  processes 
  connecting 
  the 
  summits 
  of 
  the 
  carinae 
  

   are 
  stronger 
  and 
  more 
  distant. 
  

  

  la 
  iig. 
  32 
  the 
  carinae 
  and 
  connecting 
  processes 
  are 
  very 
  much 
  

   thickened 
  and 
  present 
  the 
  appearance 
  of 
  the 
  non-celluliferous 
  

   face 
  of 
  a 
  frond 
  ; 
  on 
  removing 
  this 
  portion 
  of 
  the 
  frond 
  the 
  cell 
  

   apertures 
  become 
  exposed, 
  as 
  shown 
  in 
  the 
  lower 
  right-hand 
  

   corner 
  of 
  the 
  figure. 
  

  

  In 
  fig. 
  33 
  both 
  the 
  branches 
  and 
  dissepiments 
  are 
  carinated, 
  

   the 
  carinae 
  very 
  much 
  thickened 
  and 
  expanded 
  above, 
  presenting 
  

   the 
  same 
  appearance 
  as 
  the 
  non-celluliferous 
  face 
  of 
  the 
  frond. 
  

   There 
  is 
  even 
  a 
  more 
  gradual 
  passage 
  from 
  one 
  form 
  to 
  the 
  other 
  

   than 
  is 
  here 
  represented, 
  but 
  the 
  illustrations 
  are 
  sufficient 
  to 
  

   show 
  the 
  gradual 
  development 
  of 
  the 
  different 
  characters. 
  

  

  If 
  the 
  more 
  complex 
  forms 
  occurred 
  in 
  the 
  later 
  formations 
  and 
  

   the 
  simpler 
  in 
  the 
  earlier, 
  it 
  would 
  be 
  a 
  beautiful 
  illustration 
  of 
  

   evolution, 
  but 
  unfortunately 
  for 
  that 
  illustration 
  the 
  different 
  

   forms 
  occur 
  at 
  the 
  same 
  time, 
  the 
  most 
  simple 
  and 
  complex 
  being 
  

   frequently 
  found 
  on 
  the 
  same 
  slab 
  of 
  stone. 
  

  

  Ilemitrypa, 
  Unitrypa 
  and 
  Tectulipora 
  all 
  occur 
  in 
  the 
  Lower 
  

   Helderberg 
  group. 
  In 
  the 
  Upper 
  Helderberg 
  group, 
  more 
  

   frequently 
  than 
  in 
  any 
  other, 
  as 
  far 
  as 
  observed, 
  there 
  occur 
  

   forms 
  both 
  flabellate 
  and 
  infundibuliform, 
  in 
  which 
  some 
  of 
  the 
  

   branches 
  are 
  much 
  larger 
  than 
  the 
  others 
  ; 
  the 
  ordinary 
  branches 
  

   112 
  

  

  