﻿FROM 
  THE 
  CAMBRIAN 
  STRATA 
  OF 
  NORTH 
  AMERICA, 
  ETC. 
  141 
  

  

  however, 
  there 
  is, 
  judging 
  from 
  Dr. 
  Bornemann's 
  descriptions 
  and 
  

   figures, 
  a 
  much 
  closer 
  resemblance 
  to 
  Rugose 
  Corals 
  than 
  in 
  the 
  

   other 
  genera 
  of 
  the 
  family 
  ; 
  for 
  the 
  septa 
  and 
  wall-plates 
  are 
  imper- 
  

   forate, 
  and 
  there 
  is 
  not 
  a 
  well-defined 
  inner 
  wall 
  to 
  the 
  cup 
  or 
  tube, 
  

   the 
  central 
  portion 
  of 
  which 
  is 
  filled 
  by 
  vesicular 
  tissue. 
  

  

  In 
  the 
  non-septate 
  or 
  obscurely 
  septate 
  genera, 
  Protopliaretra 
  and 
  

   Spirocyathus, 
  the 
  resemblance 
  to 
  corals 
  is 
  far 
  less 
  striking 
  ; 
  but 
  the 
  

   reticulate 
  disposition 
  of 
  the 
  laminae 
  of 
  the 
  wall 
  in 
  these 
  forms 
  bears 
  

   a 
  singularly 
  close 
  correspondence 
  to 
  that 
  in 
  the 
  outer 
  zone 
  of 
  the 
  

   wall 
  in 
  Calostylis, 
  Lindstr., 
  and 
  other 
  later 
  perforate 
  corals. 
  In 
  these 
  

   latter 
  the 
  outer 
  reticulate 
  zone 
  passes 
  into 
  an 
  inner 
  septate 
  zone, 
  

   whereas 
  in 
  the 
  former 
  genera 
  the 
  reticulate 
  disposition 
  remains, 
  as 
  

   a 
  rule, 
  throughout 
  the 
  entire 
  thickness 
  of 
  the 
  wall, 
  though 
  occa- 
  

   sionally 
  traces 
  of 
  radiate 
  septa 
  are 
  developed. 
  The 
  thickening 
  of 
  

   the 
  wall-plates 
  in 
  Spirocyathus 
  by 
  a 
  secondary 
  deposition 
  of 
  suc- 
  

   cessive 
  layers 
  of 
  material 
  may 
  also 
  be 
  compared 
  to 
  the 
  successive 
  

   layers 
  of 
  stereoplasm 
  in 
  many 
  other 
  corals, 
  both 
  fossil 
  and 
  recent. 
  

  

  Owing 
  to 
  the 
  many 
  changes 
  induced 
  by 
  fossilization, 
  a 
  comparison 
  

   of 
  the 
  minute 
  structure 
  of 
  the 
  wall-plates 
  in 
  the 
  ArchseocyathinaB 
  

   with 
  that 
  in 
  other 
  fossil 
  corals 
  is 
  not 
  of 
  special 
  value 
  ; 
  but 
  it 
  may 
  

   be 
  noted 
  that 
  the 
  minutely 
  granular 
  carbonate 
  of 
  lime 
  of 
  which 
  the 
  

   walls 
  in 
  this 
  group 
  now 
  consist 
  is 
  likewise 
  of 
  common 
  occurrence 
  

   in 
  fossil 
  corals, 
  though 
  apparently 
  in 
  the 
  older 
  fossils 
  it 
  is 
  some- 
  

   what 
  more 
  dense 
  and 
  opaque 
  in 
  thin 
  sections. 
  

  

  The 
  above 
  considerations 
  appear 
  to 
  me 
  to 
  indicate 
  that 
  the 
  

   Archseocyathinse 
  belong 
  to 
  a 
  special 
  family 
  of 
  the 
  Zoaniharia 
  

   sclerodermata, 
  with 
  near 
  relationship 
  (leaving 
  Anthomorpha 
  out 
  of 
  

   account) 
  to 
  the 
  Perforata. 
  An 
  objection 
  may 
  be 
  taken 
  to 
  the 
  

   above 
  view 
  from 
  a 
  geological 
  standpoint, 
  since 
  other 
  undoubted 
  

   corals 
  have 
  not 
  hitherto 
  been 
  discovered 
  in 
  Cambrian 
  strata, 
  and 
  it 
  

   is 
  not 
  till 
  reaching 
  the 
  Ordovician 
  that 
  they 
  have 
  made 
  their 
  

   appearance, 
  and, 
  if 
  we 
  except 
  Calostylis, 
  perforate 
  corals 
  (com- 
  

   parable 
  to 
  Archceocyathus) 
  are 
  hardly 
  met 
  with 
  in 
  Palaeozoic 
  strata. 
  

   On 
  this 
  objection, 
  however, 
  little 
  weight 
  can 
  be 
  laid 
  ; 
  for 
  though 
  it 
  

   is 
  remarkable 
  to 
  find 
  organisms 
  with 
  such 
  a 
  general 
  correspondence 
  

   to 
  perforate 
  corals 
  in 
  the 
  lowest 
  fossiliferous 
  Cambrian 
  strata, 
  yet 
  

   they 
  are 
  in 
  association 
  with 
  Trilobites 
  and 
  other 
  fossils 
  of 
  a 
  higher 
  

   grade 
  in 
  the 
  scale 
  of 
  organized 
  life, 
  and 
  there 
  can 
  be 
  little 
  doubt 
  

   that 
  the 
  existence 
  of 
  coral 
  life 
  dates 
  back 
  to 
  a 
  period 
  long 
  anterior 
  

   to 
  the 
  deposition 
  of 
  the 
  Cambrian 
  limestones. 
  

  

  5. 
  On 
  ArchaBoscyphia, 
  gen. 
  nov., 
  Calathium, 
  Bill., 
  Trichospongia, 
  

   Bill., 
  and 
  Nipterella, 
  gen. 
  nov. 
  

  

  It 
  has 
  been 
  already 
  mentioned 
  that 
  one 
  species 
  included 
  by 
  

   Mr. 
  Billings 
  in 
  the 
  genus 
  Archceocyathus 
  {A. 
  minganensis) 
  proves 
  to 
  

   be 
  a 
  siliceous 
  sponge, 
  and 
  that 
  the 
  same 
  author 
  compared 
  the 
  

   genus 
  itself 
  with 
  Calathium, 
  Bill., 
  and 
  with 
  other 
  sponges. 
  The 
  

   Geological 
  Survey 
  of 
  Canada, 
  through 
  Mr. 
  J. 
  F. 
  Whiteaves, 
  F.G.S., 
  

   has 
  enabled 
  me 
  to 
  study 
  the 
  type 
  forms 
  of 
  A. 
  minganensis 
  and 
  of 
  

  

  