﻿The 
  Fauna 
  of 
  the 
  Niagara 
  Group. 
  Ill 
  

  

  upward 
  and 
  outward 
  ; 
  usually 
  the 
  lower 
  side 
  of 
  the 
  aperture 
  

   is 
  margined 
  by 
  a 
  projecting 
  semicircular 
  lip, 
  which 
  partially 
  

   covers 
  the 
  opening 
  ; 
  rarely 
  the 
  upper 
  margin 
  of 
  the 
  aperture 
  

   is 
  also 
  elevated. 
  

  

  This 
  is 
  the 
  most 
  common 
  form 
  of 
  the 
  genus 
  in 
  the 
  Waldron 
  

   locality, 
  and 
  is 
  very 
  abundant. 
  

  

  Trematopora 
  infrequens. 
  

  

  Plate 
  10, 
  Fig. 
  3 
  in 
  part, 
  and 
  fig. 
  4. 
  

  

  Trematopora 
  infrequens 
  Hall. 
  Doc. 
  Edit. 
  28th 
  Rep. 
  St. 
  Mus. 
  Nat. 
  Hist. 
  Expla- 
  

   nation 
  of 
  pi. 
  10, 
  figs. 
  13, 
  14 
  (in 
  error 
  for 
  3 
  and 
  4). 
  18T6. 
  

  

  Frond 
  ramose, 
  hollow, 
  the 
  inner 
  surface 
  marked 
  by 
  a 
  wrin- 
  

   kled 
  epitheca 
  ; 
  branches 
  from 
  one 
  and 
  a 
  half 
  to 
  two 
  milli- 
  

   metres 
  in 
  diameter 
  ; 
  bryozoum 
  about 
  .35 
  mm. 
  in 
  thickness. 
  

   Cell- 
  tubes 
  oval, 
  rising 
  obliquely 
  from 
  the 
  epitheca 
  to 
  the 
  ex- 
  

   terior 
  surface. 
  Length 
  of 
  aperture 
  about 
  .3 
  mm., 
  with 
  the 
  

   margin 
  distinctly 
  and 
  equally 
  elevated, 
  occasionally 
  present- 
  

   ing 
  a 
  serrated 
  appearance 
  ; 
  apertures 
  separated 
  by 
  distances 
  

   equal 
  to 
  their 
  diameters, 
  arranged 
  in 
  quincunx 
  order, 
  pre- 
  

   senting 
  a 
  spiral 
  arrangement 
  around 
  the 
  branches. 
  

  

  This 
  species 
  may 
  be 
  distinguished 
  from 
  T. 
  osculum 
  by 
  its 
  

   larger 
  cells, 
  and 
  by 
  the 
  cell-margins 
  being 
  strongly 
  and 
  

   equally 
  elevated 
  in 
  every 
  portion, 
  while 
  in 
  that 
  species 
  the 
  

   lower 
  margin 
  of 
  the 
  aperture 
  is 
  almast 
  always 
  more 
  strongly 
  

   elevated 
  than 
  the 
  upper 
  portion. 
  

  

  Trematopora 
  varia. 
  

  

  Plate 
  10, 
  Figs. 
  15-23. 
  

  

  Trematopora 
  varia 
  Hall. 
  Doe. 
  Edit. 
  28th 
  Rep. 
  St. 
  Mus. 
  Nat. 
  Hist. 
  Explanation 
  

   pi. 
  10, 
  figs. 
  15-23. 
  1876. 
  

  

  * 
  

  

  Frond 
  ramose, 
  hollow, 
  inner 
  surface 
  transversely 
  wrinkled 
  ; 
  

   branches 
  frequent, 
  from 
  two 
  to 
  seven 
  mm. 
  in 
  diameter. 
  Bry- 
  

   ozoum 
  about 
  one 
  mm. 
  in 
  thickness. 
  Cells 
  tubular, 
  oval 
  or 
  

   circular, 
  from 
  1 
  to 
  1.5 
  mm. 
  in 
  length 
  ; 
  for 
  the 
  first 
  half 
  of 
  their 
  

   extent 
  growing 
  nearly 
  parallel 
  with 
  the 
  inner 
  surface, 
  and 
  

   then 
  turning 
  abruptly 
  outward 
  ; 
  diameter 
  at 
  the 
  aperture 
  .25 
  

   mm., 
  varying 
  from 
  circular 
  to 
  elongate-oval, 
  arranged 
  irreg- 
  

   ularly 
  from 
  contiguity 
  to 
  a 
  distance 
  equal 
  to 
  the 
  diameter, 
  

   with 
  frequent 
  maculae, 
  which 
  are 
  destitute 
  of 
  cells. 
  Cell-mar- 
  

  

  