﻿146 
  DE. 
  G. 
  J. 
  HINDE 
  ON 
  AECH^EOCYATHTTS 
  AND 
  OTBZEE 
  GENEBA 
  

  

  sponges 
  occur, 
  though 
  too 
  poorly 
  preserved 
  for 
  generic 
  determination,, 
  

   large 
  masses 
  of 
  chert 
  have 
  lately 
  been 
  described 
  *, 
  thus 
  indicating 
  

   in 
  the 
  Cambrian 
  strata 
  the 
  same 
  relation 
  of 
  the 
  chert 
  to 
  the 
  

   presence 
  of 
  sponge-life 
  which 
  has 
  already 
  been 
  pointed 
  out 
  by 
  the 
  

   writer 
  in 
  the 
  Upper 
  Carboniferous 
  (Yoredale) 
  Beds 
  of 
  Ireland 
  f 
  and 
  

   in 
  rocks 
  of 
  later 
  date. 
  

  

  Stjmmaey. 
  

  

  A 
  revision 
  of 
  the 
  type 
  specimens 
  of 
  the 
  three 
  species 
  included 
  by 
  

   Mr. 
  Billings 
  in 
  the 
  genus 
  Archceocyathus 
  shows 
  that 
  each 
  of 
  the 
  

   species 
  represents 
  a 
  distinct 
  genus. 
  Archceocyathus 
  profundus 
  r 
  

   having 
  been 
  selected 
  by 
  Mr. 
  Billings 
  in 
  1865 
  as 
  the 
  typical 
  species, 
  

   is 
  retained 
  as 
  such, 
  and 
  the 
  characters 
  of 
  the 
  genus, 
  as 
  shown 
  in 
  this 
  

   species, 
  are 
  redefined. 
  Archceocyathus 
  atlanticus, 
  Billings, 
  is 
  made 
  the 
  

   type 
  of 
  a 
  new 
  genus, 
  Spirocyathus 
  ; 
  and 
  the 
  third 
  species, 
  Archceo- 
  

   cyathus 
  minganensis, 
  proves 
  to 
  be 
  a 
  siliceous 
  sponge, 
  and 
  is 
  included 
  

   in 
  a 
  new 
  genus, 
  Archceoscyphia. 
  

  

  Including 
  the 
  genera 
  allied 
  to 
  Archceocyathus, 
  described 
  by 
  Meek 
  

   and 
  Bornemann, 
  the 
  following 
  constitute 
  the 
  family 
  Archceocyathince, 
  

   proposed 
  by 
  this 
  last-named 
  author 
  : 
  — 
  Archceocyathus, 
  Bill. 
  ; 
  Ethmo- 
  

   pliyUum, 
  Meek 
  ; 
  Coscinocyathus, 
  Bornem. 
  ; 
  Anthomorpha, 
  Bornem. 
  ; 
  

   Protopharetra, 
  Bornem. 
  ; 
  and 
  Spirocyathus, 
  g. 
  n. 
  

  

  The 
  genera 
  of 
  this 
  family 
  are 
  characterized 
  for 
  the 
  most 
  part 
  by 
  

   turbinate 
  or 
  sub 
  cylindrical 
  forms 
  with 
  stout 
  walls, 
  including 
  an 
  

   interior 
  tubular 
  or 
  cup-shaped 
  cavity. 
  Their 
  skeletons 
  are 
  of 
  

   carbonate 
  of 
  lime 
  in 
  a 
  minutely 
  granular 
  condition. 
  The 
  walls 
  in 
  

   the 
  first 
  four 
  of 
  the 
  above-named 
  genera 
  consist 
  of 
  an 
  outer 
  and 
  

   an 
  inner 
  lamina 
  connected 
  by 
  vertical 
  radial 
  septa 
  ; 
  dissepiments 
  are 
  

   generally 
  present 
  between 
  the 
  septa; 
  save 
  in 
  the 
  genus 
  Antho- 
  

   morpha, 
  the 
  outer 
  lamina 
  of 
  the 
  wall 
  is 
  regularly 
  and 
  minutely 
  

   perforate, 
  and 
  the 
  inner 
  lamina 
  and 
  septa 
  are 
  likewise 
  cribriform 
  ; 
  

   EthmophyUum 
  is 
  particularly 
  distinguished 
  by 
  oblique 
  canals 
  con- 
  

   necting 
  the 
  interspaces 
  of 
  the 
  wall 
  with 
  the 
  central 
  cavity 
  ; 
  Coscino- 
  

   cyathus 
  by 
  transverse 
  perforate 
  tabulae 
  ; 
  and 
  Anthomorpha 
  by 
  the 
  

   apparently 
  imperforate 
  character 
  of 
  the 
  surface-laminae 
  and 
  septa. 
  

   Protopharetra 
  and 
  Spirocyathus 
  are 
  not 
  distinctly 
  septate, 
  but 
  their 
  

   skeletons 
  consist 
  of 
  irregularly 
  curved 
  anastomosing 
  laminae 
  and 
  

   fibres 
  ; 
  in 
  the 
  latter 
  genus 
  the 
  laminae 
  are 
  remarkably 
  thickened 
  

   by 
  successive 
  secondary 
  deposits 
  of 
  calcareous 
  material. 
  

  

  The 
  Archaeocyathinae 
  are 
  regarded 
  as 
  a 
  special 
  family 
  of 
  the 
  Zoan- 
  

   tharia 
  sclerodermata, 
  in 
  some 
  features 
  allied 
  to 
  the 
  group 
  of 
  per- 
  

   forate 
  Corals. 
  The 
  family 
  is 
  restricted, 
  so 
  far 
  as 
  known 
  at 
  present, 
  

   to 
  the 
  lowest 
  fossiliferous 
  zone 
  of 
  the 
  Cambrian 
  strata, 
  that 
  cha- 
  

   racterized 
  by 
  the 
  trilobitic 
  genus 
  Olenellus, 
  Hall, 
  and 
  it 
  occurs 
  at 
  

   Anse 
  au 
  Loup, 
  Labrador 
  ; 
  Troy, 
  New 
  York 
  State 
  ; 
  Nevada 
  ; 
  Sierra 
  

   Morena, 
  Spain 
  ; 
  and 
  in 
  the 
  south-west 
  of 
  the 
  Island 
  of 
  Sardinia. 
  

  

  * 
  " 
  Recent 
  work 
  of 
  the 
  Geol. 
  Survey 
  in 
  the 
  N.W. 
  Highlands 
  of 
  Scotland,'* 
  

   Quart. 
  Journ. 
  Geol. 
  Soc. 
  toL 
  xliv. 
  1888, 
  pp. 
  404, 
  406, 
  407. 
  

  

  t 
  Geol. 
  Mag. 
  vol. 
  iv. 
  1887, 
  p. 
  435 
  ; 
  ib. 
  vol. 
  v. 
  1858 
  ; 
  Phil. 
  Trans. 
  1885, 
  pt. 
  ii. 
  

   pp. 
  403-453. 
  

  

  