﻿FROM 
  THE 
  CAMBRIAN 
  STRATA 
  OF 
  NORTH 
  AMERICA, 
  ETC. 
  147 
  

  

  The 
  genus 
  Archceoscyphia, 
  based 
  on 
  Archceocyathus 
  minganensis. 
  

   Bill., 
  is 
  shown 
  to 
  be 
  a 
  Lithistid 
  sponge 
  ; 
  and 
  Nipterella, 
  n. 
  g., 
  based 
  

   on 
  Calathium 
  (?) 
  jparadoocicum 
  belongs 
  likewise 
  to 
  the 
  same 
  group 
  

   of 
  sponges. 
  The 
  genera 
  Calathium, 
  Bill., 
  and 
  Trichospongia, 
  Bill., 
  

   are 
  also 
  undoubted 
  siliceous 
  sponges. 
  These 
  various 
  sponges, 
  which 
  

   were 
  either 
  included 
  in 
  Archceocyathus 
  by 
  Billings 
  or 
  regarded 
  

   as 
  allied 
  thereto, 
  have 
  no 
  relation 
  whatever 
  to 
  this 
  genus 
  or 
  to 
  

   any 
  member 
  of 
  the 
  family 
  in 
  which 
  it 
  is 
  included. 
  They 
  likewise 
  

   come 
  from 
  a 
  distinctly 
  higher 
  geological 
  horizon, 
  that 
  of 
  the 
  Cal- 
  

   eiferous 
  Formation 
  of 
  the 
  Canadian 
  geologists, 
  which 
  is 
  probably 
  at 
  

   the 
  summit 
  of 
  the 
  Cambrian 
  system. 
  They 
  are 
  found 
  in 
  this 
  for- 
  

   mation 
  in 
  the 
  Mingan 
  Islands, 
  Lower 
  St. 
  Lawrence, 
  and 
  in 
  New- 
  

   foundland 
  : 
  species 
  of 
  Archceoscyphia 
  and 
  Calathium 
  are 
  also 
  present 
  

   in 
  the 
  Durness 
  Limestones 
  of 
  the 
  North-west 
  of 
  Scotland, 
  but 
  I 
  

   have 
  not 
  seen 
  any 
  undoubted 
  examples 
  of 
  Archceocyathus 
  associated 
  

   with 
  them. 
  

  

  EXPLANATION 
  OF 
  PLATE 
  V. 
  

  

  Fig. 
  1. 
  Archceocyathus 
  profundus, 
  Bill. 
  A 
  specimen 
  showing 
  the 
  outer 
  form 
  

   and 
  traces 
  of 
  the 
  septa 
  ; 
  the 
  surface 
  has 
  been 
  weathered. 
  Natural 
  

   size. 
  From 
  the 
  Cambrian 
  strata 
  at 
  Anse 
  au 
  Loup, 
  Labrador. 
  The 
  

   specimen 
  belongs 
  to 
  the 
  Museum 
  of 
  McGill 
  College, 
  Montreal. 
  

  

  Fig. 
  2. 
  The 
  same. 
  A 
  saucer-shaped 
  specimen, 
  viewed 
  from 
  above. 
  The 
  

   radiating 
  septa 
  and 
  dissepiments 
  now 
  appear 
  as 
  depressed 
  lines 
  in 
  the 
  

   matrix. 
  Natural 
  size. 
  Also 
  from 
  Anse 
  au 
  Loup, 
  Labrador. 
  The 
  

   specimen 
  belongs 
  to 
  the 
  Collection 
  of 
  the 
  Geological 
  Survey 
  of 
  Canada, 
  

   Ottawa. 
  

  

  Fig. 
  3. 
  The 
  same. 
  Portion 
  of 
  a 
  transverse 
  section 
  of 
  a 
  specimen 
  drawn 
  from 
  a 
  

   microscopic 
  section, 
  and 
  enlarged 
  four 
  diameters. 
  The 
  immediate 
  

   outer 
  surface 
  is 
  not 
  preserved 
  ; 
  the 
  vesicular 
  tissue 
  next 
  the 
  central 
  

   cavity 
  is 
  largely 
  developed. 
  The 
  specimen 
  is 
  from 
  Anse 
  au 
  Loup, 
  

   and 
  belongs 
  to 
  the 
  Geological 
  Survey 
  of 
  Canada. 
  

  

  Fig. 
  4. 
  The 
  same. 
  A 
  fragment 
  of 
  the 
  transverse 
  section 
  of 
  a 
  cup-shaped 
  speci- 
  

   men, 
  enlarged 
  ten 
  diameters, 
  showing 
  below 
  a 
  slight 
  development 
  of 
  

   vesicular 
  tissue 
  and 
  a 
  definite 
  inner 
  lamina 
  of 
  the 
  wall. 
  The 
  section 
  

   belongs 
  to 
  the 
  Geological 
  Survey 
  of 
  Canada. 
  

  

  Fig. 
  5. 
  The 
  same. 
  Portion 
  of 
  a 
  longitudinal 
  section 
  of 
  the 
  wall 
  of 
  the 
  same 
  

   specimen, 
  showing 
  in 
  places 
  the 
  perforations 
  in 
  the 
  septa 
  and 
  the 
  

   dissepiments. 
  Enlarged 
  five 
  diameters. 
  From 
  Anse 
  au 
  Loup, 
  

   Labrador. 
  The 
  specimen 
  belongs 
  to 
  the 
  Geological 
  Survey 
  of 
  

   Canada. 
  

  

  Fig. 
  6. 
  Archceocyathus 
  ichnusce, 
  Meneghini. 
  A 
  portion 
  of 
  the 
  outer 
  surface 
  of 
  

   the 
  wall, 
  showing 
  the 
  minute 
  perforations 
  between 
  the 
  septa. 
  Enlarged 
  

   forty 
  diameters. 
  From 
  Cambrian 
  strata 
  at 
  Punta 
  Pintau, 
  Sardinia. 
  

  

  Fig. 
  7. 
  Ethmophyllum 
  Whitneyi, 
  Meek. 
  Portion 
  of 
  a 
  microscopic 
  transverse 
  

   section 
  of 
  a 
  specimen, 
  enlarged 
  ten 
  diameters, 
  showing 
  the 
  septa 
  and 
  

   the 
  oblique 
  inner 
  canals 
  of 
  the 
  wall 
  in 
  section. 
  From 
  the 
  Cambrian 
  

   strata 
  of 
  Nevada. 
  [This 
  figure 
  has 
  been 
  introduced 
  since 
  the 
  paper 
  

   was 
  read 
  before 
  the 
  Society.] 
  

  

  Fig. 
  8. 
  Spirocyathus 
  atlanticus, 
  Bill., 
  sp. 
  Portion 
  of 
  a 
  transverse 
  section, 
  

   enlarged 
  four 
  diameters, 
  showing 
  the 
  arrangement 
  of 
  the 
  laminae 
  of 
  

   the 
  wall 
  ; 
  for 
  the 
  most 
  part 
  irregular, 
  but 
  apparently 
  radial 
  in 
  some 
  

   places. 
  From 
  the 
  type 
  form 
  belonging 
  to 
  the 
  Geological 
  Survey 
  of 
  

   Canada. 
  

  

  Fig. 
  9. 
  The 
  same. 
  Portion 
  of 
  a 
  longitudinal 
  section 
  of 
  the 
  wall 
  of 
  the 
  type 
  

   specimen, 
  from 
  Anse 
  au 
  Loup, 
  Labrador. 
  Enlarged 
  four 
  diameters. 
  

   It 
  belongs 
  to 
  the 
  Geological 
  Survey 
  of 
  Canada. 
  

  

  12 
  

  

  