﻿FROM 
  THE 
  CAMBRIAN 
  STRATA 
  OF 
  NORTH 
  AMERICA, 
  ETC. 
  127 
  

  

  Dr. 
  J. 
  W. 
  Dawson 
  *, 
  on 
  the 
  other 
  hand, 
  found 
  a 
  structural 
  re- 
  

   semblance 
  to 
  Foraminifera 
  in 
  the 
  microscopic 
  characters 
  of 
  A. 
  atlan- 
  

   ticus 
  and 
  A. 
  profundus. 
  

  

  In 
  1868 
  t, 
  Prof. 
  Meek 
  described 
  as 
  the 
  types 
  of 
  a 
  new 
  family 
  of 
  

   corals 
  some 
  fossils 
  from 
  the 
  Cambrian 
  rocks 
  of 
  Nevada, 
  for 
  which 
  

   the 
  genus 
  Etlimophyllum 
  was 
  proposed. 
  Shortly 
  afterwards 
  J, 
  the 
  

   same 
  author 
  stated 
  that 
  they 
  were 
  probably 
  not 
  generically 
  distinct 
  

   from 
  Archceocyathus, 
  Bill., 
  since 
  they 
  agree 
  very 
  closely 
  in 
  internal 
  

   structure 
  with 
  A. 
  minganensis 
  and 
  A. 
  profundus. 
  No 
  definite 
  dia- 
  

   gnosis 
  was 
  given 
  of 
  Etlimophyllum 
  apart 
  from 
  the 
  specific 
  characters, 
  

   aud 
  no 
  figures 
  accompanied 
  the 
  paper. 
  It 
  seems 
  probable, 
  how- 
  

   ever, 
  that 
  the 
  species 
  described 
  by 
  Prof. 
  Meek 
  included 
  more 
  than 
  

   one 
  generic 
  type, 
  since 
  it 
  is 
  stated 
  that 
  in 
  the 
  interior 
  of 
  some 
  there 
  

   were 
  observed 
  appearances 
  of 
  transverse 
  plates, 
  whilst 
  in 
  others 
  

   there 
  was 
  a 
  dense 
  vesicular 
  tissue. 
  Mention 
  is 
  also 
  made 
  of 
  obliquely 
  

   directed 
  canals 
  passing 
  through 
  the 
  inner 
  wall, 
  which 
  in 
  transverse 
  

   sections 
  appear 
  as 
  a 
  double 
  row 
  of 
  vesicles 
  — 
  -structures 
  which 
  are 
  

   not 
  found 
  in 
  any 
  of 
  Mr. 
  Billings's 
  types. 
  

  

  In 
  1873 
  § 
  Mr. 
  8. 
  W. 
  Ford 
  proposed 
  the 
  genus 
  Archceocyathellus, 
  

   and 
  in 
  1878 
  || 
  the 
  genus 
  Protocyathus 
  for 
  some 
  small 
  imperfectly 
  

   preserved 
  forms 
  from 
  the 
  Cambrian 
  strata 
  of 
  Troy, 
  New 
  York. 
  

   They 
  are 
  admittedly 
  very 
  closely 
  allied 
  to 
  Archceocyathus, 
  and 
  the 
  

   generic 
  characters 
  are 
  mainly 
  based 
  on 
  the 
  nature 
  and 
  arrangement 
  

   of 
  the 
  pores 
  in 
  the 
  outer 
  surface 
  of 
  the 
  wall, 
  features 
  which, 
  though, 
  

   of 
  specific, 
  are 
  hardly 
  of 
  generic 
  importance. 
  

  

  In 
  1876 
  % 
  Prof, 
  de 
  Koninck 
  refers 
  doubtfully 
  to 
  Archceocyathus 
  

   some 
  fossils 
  from 
  the 
  Palaeozoic 
  strata 
  of 
  Australia, 
  supposed 
  to 
  be 
  

   of 
  Devonian 
  age. 
  Judging 
  from 
  the 
  description 
  and 
  figures, 
  no 
  

   definite 
  opinion 
  can 
  be 
  formed 
  as 
  to 
  their 
  real 
  characters. 
  

  

  In 
  1878 
  ** 
  Prof. 
  H. 
  A. 
  Nicholson 
  places 
  Archceocyathus 
  among 
  the 
  

   Spongida, 
  referring 
  more 
  particularly 
  to 
  the 
  spicules 
  found 
  in 
  con- 
  

   nexion 
  with 
  A. 
  minganensis. 
  Though, 
  as 
  will 
  be 
  shown 
  in 
  the 
  

   sequel, 
  this 
  particular 
  species 
  is 
  a 
  true 
  sponge, 
  it 
  is 
  radically 
  different 
  

   from 
  A. 
  profundus, 
  which 
  is 
  taken 
  as 
  the 
  type 
  of 
  Archceocyathus 
  

   proper. 
  

  

  In 
  1879ft 
  Prof. 
  v. 
  Zittel 
  places 
  Archceocyathus 
  together 
  with 
  Cal- 
  

   athium 
  in 
  the 
  Euretid 
  family 
  of 
  Hexactinellid 
  sponges 
  ; 
  he 
  states, 
  

   however, 
  that 
  their 
  structures 
  are 
  unknown 
  and 
  their 
  true 
  position 
  

   doubtful. 
  At 
  a 
  later 
  date 
  JJ, 
  the 
  view 
  of 
  F\ 
  Homer, 
  mentioned 
  

   below, 
  is 
  given, 
  but 
  without 
  comment. 
  

  

  * 
  Can. 
  Nat. 
  and 
  Geol. 
  1865, 
  p. 
  103, 
  note 
  ; 
  also 
  quoted 
  by 
  Billings 
  in 
  Pal. 
  

  

  vol. 
  i. 
  p. 
  356. 
  

  

  + 
  Amer. 
  Journ. 
  Sci. 
  and 
  Arts, 
  2nd 
  sei\ 
  vol. 
  xliv. 
  (1868), 
  p. 
  62. 
  

   \ 
  Id. 
  vol. 
  xlvi. 
  (1868), 
  p. 
  144. 
  

   § 
  Id. 
  3rd 
  ser. 
  vol. 
  v. 
  (1873), 
  p. 
  211, 
  fig. 
  1. 
  

   || 
  Id. 
  vol. 
  xv. 
  (1878), 
  p. 
  124, 
  figs, 
  la, 
  b. 
  

  

  «j[ 
  Recherches 
  sur 
  les 
  fossiles 
  paleozoiques 
  de 
  la 
  Nouvelle-Galles 
  du 
  Sud, 
  

   1876-7, 
  p. 
  68, 
  pi. 
  ii. 
  fig. 
  1. 
  

  

  ** 
  Manual 
  of 
  Paleontology, 
  2nd 
  ed. 
  (1878), 
  vol. 
  i. 
  p. 
  139. 
  

   tt 
  Handbuch 
  der 
  Pal. 
  vol. 
  i. 
  2nd 
  pt. 
  (1879), 
  pp. 
  173, 
  195. 
  

   X\ 
  Id. 
  Appendix 
  (1880), 
  p. 
  728. 
  

  

  