﻿886 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  ments 
  is 
  essentially 
  one 
  and 
  the 
  same 
  thing 
  ; 
  in 
  fact, 
  from 
  differ- 
  

   ent 
  specimens 
  a 
  regular 
  gradation 
  can 
  be 
  observed 
  from 
  the 
  

   anastomosing 
  of 
  the 
  branches 
  to 
  connection 
  by 
  very 
  slender 
  

   dissepiments, 
  as 
  will 
  be 
  seen 
  from 
  the 
  following 
  figures 
  : 
  

  

  In 
  one 
  species 
  from 
  the 
  Niagara 
  group 
  from 
  Waldron, 
  

   Indiana, 
  we 
  have 
  on 
  the 
  same 
  frond 
  both 
  anastomosis 
  of 
  

  

  branches 
  and 
  connection 
  by 
  slender, 
  

   noncelluliferous 
  dissepiments, 
  and 
  also 
  

   by 
  wide 
  celluliferous 
  dissepiments, 
  

   one 
  specimen 
  having 
  on 
  different 
  

   portions 
  of 
  the 
  frond 
  the 
  characters 
  

   of 
  Reteporella 
  (see 
  figs. 
  11 
  and 
  12), 
  

   Phyllopora 
  and 
  Polypora. 
  

  

  The 
  typical 
  species 
  of 
  the 
  genus 
  

   Polypora, 
  McCoy, 
  is 
  distinguished 
  from 
  

   the 
  typical 
  species 
  of 
  Fenestella 
  by 
  the 
  

   numerous 
  rows 
  of 
  cell 
  apertures 
  and 
  

   the 
  absence 
  of 
  a 
  median 
  carina. 
  The 
  typical 
  species 
  of 
  each 
  

   genus 
  are 
  well 
  defined 
  and 
  easily 
  distinguished 
  from 
  each 
  

  

  other, 
  but 
  there 
  are 
  numerous 
  forms 
  intermediate 
  between 
  

   these 
  two 
  extremes, 
  and 
  as 
  the 
  genera 
  are 
  now 
  constituted, 
  it 
  is 
  

   a 
  perplexing 
  question 
  to 
  which 
  genus 
  some 
  of 
  the 
  forms 
  belong. 
  

  

  