﻿Report 
  ot 
  the 
  State 
  Geologist. 
  917 
  

  

  In 
  examining 
  specimens 
  from 
  the 
  Falls 
  of 
  the 
  Ohio, 
  I 
  have 
  

   occasionally 
  met 
  with 
  individuals 
  of 
  the 
  genus 
  Fenestella 
  having 
  

   one 
  margin 
  much 
  thickened 
  and 
  with 
  a 
  tendency 
  to 
  a 
  spiral 
  

   mode 
  of 
  growth, 
  but 
  they 
  were 
  only 
  aberrant 
  forms 
  of 
  well- 
  

   known 
  species. 
  

  

  If 
  several 
  specimens 
  of 
  this 
  species 
  have 
  been 
  found 
  and 
  the 
  

  

  form 
  is 
  persistent, 
  it 
  will 
  be 
  interesting 
  as 
  the 
  first 
  step 
  in 
  the 
  

  

  gradual 
  change 
  from 
  the 
  typical 
  Fenestella 
  to 
  Archimedes, 
  

  

  Archimedes 
  laxus 
  being 
  another 
  step 
  toward 
  the 
  typical 
  form 
  of 
  

  

  Archimedes. 
  

  

  AKCHIMEDIOPOKA, 
  D'Orbigny. 
  

  

  The 
  structural 
  character 
  or 
  the 
  remains 
  of 
  fenestrules 
  on 
  the 
  

  

  axis, 
  as 
  seen 
  in 
  Dr. 
  Owen's 
  figure, 
  have 
  been 
  mistaken 
  by 
  d'Or- 
  

  

  bigny 
  for 
  the 
  animal 
  cells, 
  and 
  upon 
  this 
  character 
  he 
  proposed 
  

  

  the 
  new 
  genus 
  Archimediopora, 
  having 
  the 
  cells 
  arranged 
  upon 
  

  

  the 
  salient 
  angles 
  of 
  the 
  spiral 
  band. 
  

  

  LYKOPORA, 
  Hall. 
  

  

  The 
  genus 
  Lyropora 
  was 
  first 
  described 
  by 
  Prof. 
  James 
  Hall 
  

   (Proc. 
  Amer. 
  Acad. 
  Sciences, 
  1857, 
  p. 
  179; 
  no 
  illustrations.) 
  

   "Bryozoum 
  consisting 
  of 
  foliated 
  reticulated 
  expansions, 
  mar- 
  

   gined 
  on 
  either 
  side 
  by 
  strong 
  stony 
  supports, 
  which 
  diverge 
  from 
  

   the 
  base, 
  curving 
  outward 
  and 
  upward. 
  The 
  foliate 
  expansion 
  is 
  

   spread 
  out 
  between 
  these 
  diverging 
  arms, 
  which 
  are 
  themselves 
  

   formed 
  by 
  the 
  coalescing 
  and 
  thickening 
  of 
  the 
  branches. 
  The 
  

   growth 
  of 
  these 
  strong 
  supports 
  is 
  sometimes 
  direct 
  or 
  in 
  a 
  line 
  

   parallel 
  with 
  the 
  point 
  of 
  attachment 
  ; 
  and 
  in 
  other 
  cases 
  there 
  

   is 
  at 
  first 
  a 
  receding 
  of 
  the 
  whole 
  from 
  that 
  point, 
  an 
  extreme 
  

   thickening 
  of 
  the 
  supports 
  on 
  one 
  side 
  and 
  a 
  gradual 
  narrowing 
  

   to 
  the 
  opposite 
  points 
  where 
  the 
  branches 
  originate. 
  

  

  " 
  These 
  bifurcating 
  processes 
  with 
  the 
  point 
  of 
  attachment 
  

   resemble 
  the 
  lower 
  jaw 
  of 
  the 
  common 
  frog, 
  and 
  are 
  known 
  

   along 
  the 
  Mississippi 
  valley 
  as 
  the 
  ' 
  frog-mouth 
  coral.' 
  " 
  

  

  Fenestella 
  ladus, 
  the 
  typical 
  species, 
  has 
  the 
  branches 
  round 
  

   and 
  with 
  four 
  or 
  five 
  rows 
  of 
  cell 
  apertures. 
  

  

  LYKOPORHSTA, 
  nov. 
  gen. 
  

   The 
  typical 
  species 
  of 
  Lyropora 
  has 
  three 
  or 
  more 
  ranges 
  of 
  

   cell 
  apertures 
  ; 
  other 
  species 
  haVe 
  only 
  two 
  ranges 
  ; 
  for 
  these 
  

   forms 
  I 
  propose 
  the 
  name 
  Lyroporina. 
  They 
  have 
  the 
  same 
  rela- 
  

   tion 
  to 
  Lyropora 
  as 
  has 
  the 
  genus 
  Fenestella 
  to 
  Polypora. 
  

  

  