﻿The 
  Fatoa 
  of 
  the 
  Niagara 
  Group. 
  105 
  

  

  ASTYLOSPONGIA 
  (PALCEOMANON) 
  BUESA. 
  

  

  Plate 
  3, 
  Figs. 
  15, 
  16. 
  

  

  Astylospongia? 
  (Palceomanon) 
  bursa 
  Hall,. 
  Doc. 
  Edit. 
  28th 
  Rep. 
  St. 
  Mus. 
  Nat. 
  

  

  Hist. 
  Explanation 
  of 
  pi. 
  3, 
  figs. 
  15, 
  16. 
  1876. 
  

   Compare 
  Palceomanon 
  cratera 
  Roemer. 
  Die 
  Silur. 
  Faun, 
  des 
  Westl. 
  Tenn., 
  p. 
  13, 
  

  

  pi. 
  1, 
  f. 
  4, 
  4a. 
  1860. 
  Also 
  Aulacopina 
  Oranti 
  Billings. 
  Canadian 
  Naturalist 
  

  

  and 
  Geologist, 
  1875. 
  

  

  Body 
  calyciform, 
  elongate 
  semi-elliptical 
  in 
  outline, 
  regu- 
  

   larly 
  rounded 
  below 
  and 
  curving 
  upwards, 
  the 
  sides 
  above 
  the 
  

   middle 
  of 
  the 
  height 
  nearly 
  straight. 
  

  

  Surface 
  finely 
  punctate 
  and 
  marked 
  by 
  elongate 
  sub 
  conflu- 
  

   ent 
  pits. 
  

  

  The 
  specimen 
  figured 
  has 
  been 
  laterally 
  compressed, 
  so 
  that 
  

   the 
  true* 
  form 
  would 
  be 
  narrower 
  than 
  represented 
  in 
  figure 
  

   15. 
  Some 
  specimens 
  of 
  recent 
  collections 
  with 
  shorter 
  and 
  

   comparatively 
  broader 
  cups, 
  have 
  essentially 
  the 
  same 
  general 
  

   aspect 
  of 
  surface 
  as 
  this 
  ; 
  but 
  the 
  large 
  pits 
  upon 
  the 
  sur- 
  

   face 
  are 
  less 
  confluent, 
  and 
  it 
  is 
  possible 
  that 
  these 
  forms 
  may 
  

   be 
  allied 
  to 
  Palceomanon 
  cratera 
  of 
  Roemer, 
  but 
  their 
  condi- 
  

   tion 
  of 
  preservation 
  does 
  not 
  admit 
  of 
  satisfactory 
  reference. 
  

  

  A 
  single 
  specimen 
  with 
  a 
  proportionally 
  narrower 
  form 
  than 
  

   shown 
  in 
  fig. 
  15, 
  presents, 
  on 
  a 
  part 
  of 
  its 
  surface, 
  numerous 
  

   and 
  closely 
  arranged 
  stelliform 
  spiculse 
  which 
  appear 
  to 
  be 
  

   superficial, 
  while 
  the 
  surface 
  beneath 
  is 
  finely 
  punctate. 
  

  

  The 
  imperfect 
  preservation 
  of 
  all 
  the 
  larger 
  forms 
  of 
  sponges 
  

   in 
  the 
  Waldron 
  collections 
  is 
  such 
  as 
  to 
  render 
  difficult 
  and 
  

   unsatisfactory 
  any 
  specific 
  determinations 
  from 
  external 
  form 
  

   and 
  character 
  alone. 
  

  

  