﻿The 
  Fauna 
  of 
  the 
  Niagara 
  Group. 
  . 
  125 
  

  

  poriferous 
  side. 
  Cell-apertures 
  small, 
  circular, 
  in 
  two 
  ranges, 
  

   distant 
  from 
  each 
  other 
  more 
  than 
  their 
  diameter, 
  opening 
  

   nearly 
  directly 
  upward 
  ; 
  margins 
  distinctly 
  elevated 
  and 
  in- 
  

   denting 
  the 
  border 
  of 
  the 
  fenestrule. 
  Space 
  between 
  the 
  ranges 
  

   of 
  cells 
  carinate, 
  the 
  carina 
  thin 
  and 
  elevated, 
  abruptly 
  ex- 
  

   panding 
  on 
  each- 
  side 
  above, 
  and 
  again 
  narrowing 
  to 
  a 
  thin 
  

   carina. 
  

  

  The 
  elevated 
  and 
  expanded 
  carina 
  which 
  is 
  again 
  carinate, 
  

   and 
  the 
  partial 
  closing 
  of 
  the 
  fenestrules 
  on 
  the 
  poriferous 
  

   side 
  are 
  characteristics 
  of 
  this 
  species. 
  

  

  The 
  specimen, 
  Fenestella 
  spf 
  fig. 
  14, 
  ut 
  cit., 
  proves 
  to 
  be 
  

   identical 
  with 
  undoubted 
  Fenestella 
  acmea, 
  and 
  diners 
  from 
  

   F. 
  bellastriata 
  n. 
  sp. 
  in 
  its 
  regular 
  oval 
  fenestrules, 
  having 
  a 
  

   length 
  never 
  greater 
  than 
  twice 
  the 
  width, 
  and 
  eight 
  to 
  nine 
  

   fenestrules 
  in 
  the 
  space 
  of 
  5 
  mm. 
  In 
  F. 
  bellastriata 
  there 
  

   are 
  six 
  fenestrules 
  in 
  the 
  space 
  of 
  5 
  mm., 
  and 
  they* 
  have 
  

   always 
  a 
  length 
  greater 
  than 
  twice 
  the 
  width. 
  

  

  A 
  small 
  fragment 
  of 
  the 
  poriferous 
  side 
  of 
  the 
  specimen 
  

   figured 
  presents 
  the 
  character 
  of 
  F. 
  acmea. 
  

  

  Fenestella 
  punctostriata. 
  

  

  Plate 
  12, 
  Figs. 
  15, 
  16. 
  

  

  Fenestella 
  punctostriata 
  Hall. 
  Doc. 
  Edit. 
  28th 
  Rep. 
  St. 
  Mus. 
  Nat. 
  Hist. 
  Ex- 
  

   planation 
  of 
  pi. 
  12, 
  figs. 
  15, 
  16. 
  1876. 
  

  

  Frond 
  flabelliform, 
  branches 
  strong, 
  six 
  in 
  the 
  space 
  of 
  5 
  

   mm.; 
  on 
  non-poriferous 
  side 
  rounded, 
  striated 
  ; 
  striae 
  very 
  dis- 
  

   tinct, 
  five 
  to 
  ten' 
  on 
  each 
  branch, 
  finely 
  granulose. 
  Dissepi- 
  

   ments 
  variable, 
  sometimes 
  slender, 
  often 
  thickened, 
  and 
  the 
  

   branches 
  sometimes 
  anastomosing 
  from 
  lateral 
  contact. 
  Fen- 
  

   estrules 
  variable 
  in 
  shape, 
  width 
  about 
  the 
  same 
  as 
  the 
  

   branches, 
  length 
  from 
  three 
  to 
  ^ve 
  times 
  their 
  width. 
  Cell- 
  

   pores 
  in 
  from 
  three 
  to 
  ^ve 
  ranges, 
  five 
  or 
  six 
  pores 
  in 
  the 
  

   length 
  of 
  a 
  fenestrule. 
  Apertures 
  polygonal, 
  contiguous 
  and 
  

   alternating, 
  forming 
  oblique 
  rows 
  across 
  the 
  branch 
  ; 
  parti- 
  

   tions 
  thin, 
  sharp 
  and 
  slightly 
  granulose. 
  

  

  T 
  i 
  

  

  'he 
  poriferous 
  side 
  of 
  the 
  frond 
  of 
  this 
  species 
  was 
  unknown 
  

   at 
  the 
  time 
  of 
  giving 
  the 
  illustrations 
  on 
  plate 
  12. 
  The 
  study 
  

   of 
  many 
  specimens 
  shows 
  that 
  there 
  is 
  considerable 
  variation 
  

   in 
  the 
  fenestrules, 
  which 
  is 
  not 
  indicated 
  in 
  fig. 
  15. 
  The 
  

   striato-punctate 
  character 
  of 
  the 
  non-poriferous 
  side, 
  and 
  the 
  

   poriferous 
  side 
  with 
  large 
  angalar 
  cellules 
  in 
  more 
  than 
  two 
  

   rows, 
  are 
  distinguishing 
  features 
  of 
  the 
  species. 
  

  

  