﻿FROM 
  THE 
  LOWER 
  SILURIAN 
  OP 
  NORTH 
  AMERICA. 
  505 
  

  

  tomously 
  at 
  short 
  intervals. 
  Corallites 
  very 
  small 
  and 
  crowded, 
  

   from 
  ten 
  to 
  twelve 
  in 
  the 
  space 
  of 
  1 
  line, 
  thick-walled, 
  opening 
  

   obliquely 
  on 
  the 
  surface 
  by 
  oval 
  or- 
  circular 
  calices, 
  between 
  which 
  

   are 
  placed 
  excessively 
  minute 
  circular 
  tubuli. 
  The 
  surface 
  exhibits 
  

   no 
  elevations 
  or 
  tubercles, 
  but 
  is 
  entirely 
  smooth 
  ; 
  and 
  there 
  are 
  also 
  

   no 
  groups 
  of 
  larger-sized 
  corallites, 
  the 
  ordinary 
  corallites 
  being 
  all 
  

   nearly 
  of 
  a 
  size. 
  

  

  This 
  species 
  is 
  allied 
  to 
  C. 
  Fletcheri, 
  Edw. 
  & 
  H., 
  from 
  which 
  it 
  is 
  

   distinguished 
  by 
  the 
  thick-walled 
  nearly 
  equal 
  corallites, 
  and 
  the 
  

   oblique 
  and 
  very 
  small 
  calices, 
  the 
  dimensions 
  of 
  which 
  are 
  much 
  

   more 
  minute 
  than 
  in 
  the 
  latter 
  form. 
  My 
  description 
  is 
  drawn 
  from 
  

   type 
  specimens 
  furnished 
  by 
  Mr. 
  U. 
  P. 
  James. 
  

  

  Locality 
  and 
  Formation. 
  Cincinnati 
  group, 
  near 
  Cincinnati, 
  Ohio. 
  

  

  8. 
  CHiETETES 
  delicattjlus, 
  Nich. 
  PI. 
  XXIX. 
  figs. 
  8, 
  8 
  a, 
  8 
  b. 
  

  

  Corallum 
  very 
  slender 
  and 
  delicate, 
  ramose, 
  composed 
  of 
  cylindri- 
  

   cal 
  stems, 
  terminating 
  in 
  rounded, 
  sometimes 
  thickened 
  extremities, 
  

   and 
  apparently 
  springing 
  in 
  some 
  cases 
  from 
  a 
  horizontal 
  footstalk. 
  

   Stems 
  sometimes 
  apparently 
  simple, 
  more 
  commonly 
  branched 
  di- 
  

   chotomously, 
  the 
  division 
  taking 
  place 
  at 
  acute 
  angles 
  ; 
  diameter 
  of 
  

   the 
  stems 
  and 
  branches 
  from 
  one 
  quarter 
  of 
  a 
  line 
  to 
  half 
  a 
  line, 
  

   rarely 
  reaching 
  two 
  thirds 
  of 
  a 
  line. 
  Corallites 
  very 
  oblique 
  to 
  the 
  

   surface, 
  opening 
  by 
  oval 
  apertures, 
  the 
  length 
  of 
  which 
  corresponds 
  

   with 
  the 
  axis 
  of 
  the 
  stem 
  and 
  exceeds 
  the 
  breadth. 
  Calices 
  in 
  dia- 
  

   gonal 
  rows, 
  about 
  eight 
  in 
  1 
  line 
  measured 
  longitudinally, 
  and 
  from 
  

   twelve 
  to 
  fourteen 
  in 
  the 
  same 
  space 
  measured 
  diagonally. 
  When 
  

   perfect 
  and 
  unworn, 
  the 
  lower 
  lip 
  of 
  the 
  calices 
  is 
  thin 
  and 
  prominent. 
  

   The 
  calices 
  are 
  all 
  of 
  equal 
  size 
  ; 
  and 
  the 
  surface 
  is 
  destitute 
  of 
  

   monticules 
  or 
  tubercles. 
  

  

  This 
  is 
  one 
  of 
  the 
  commonest 
  fossils 
  of 
  the 
  Hudson-Pi 
  ver 
  forma- 
  

   tion, 
  both 
  in 
  Canada 
  and 
  in 
  the 
  United 
  States. 
  From 
  its 
  very 
  

   minute 
  size, 
  I 
  am 
  left 
  somewhat 
  uncertain 
  as 
  to 
  the 
  true 
  position 
  of 
  

   this 
  abundant 
  little 
  fossil. 
  It 
  is, 
  I 
  think, 
  certainly 
  the 
  form 
  which 
  

   has 
  generally 
  been 
  quoted 
  as 
  a 
  slender 
  variety 
  of 
  Stenopora 
  fibrosa 
  ; 
  

   but 
  even 
  if 
  this 
  species 
  were 
  to 
  be 
  retained, 
  our 
  examples 
  could 
  not 
  

   be 
  placed 
  under 
  it. 
  It 
  is 
  likewise 
  apparently 
  one 
  of 
  the 
  forms 
  

   which 
  has 
  been 
  figured 
  by 
  Hall 
  under 
  the 
  name 
  of 
  Ch&tetes 
  lyco- 
  

   joerdon 
  (Pal. 
  X. 
  Y. 
  vol. 
  i. 
  pi. 
  24. 
  fig. 
  1 
  k, 
  cast, 
  excl.). 
  It 
  is 
  most 
  

   closely 
  allied 
  to 
  Chcetetes 
  gracilis, 
  James 
  ; 
  but 
  it 
  is 
  readily 
  separated 
  

   by 
  the 
  absence 
  of 
  minute 
  tubuli 
  interspersed 
  amongst 
  the 
  larger 
  

   corallites, 
  by 
  the 
  much 
  greater 
  obliquity 
  of 
  tbe 
  corallites 
  and 
  their 
  

   much 
  thinner 
  walls, 
  and 
  by 
  the 
  uniformly 
  slender 
  habit 
  and 
  stunted 
  

   growth. 
  From 
  C. 
  Fletcheri, 
  Edw. 
  & 
  H., 
  it 
  is 
  also 
  distinguished 
  by 
  

   the 
  uniformity 
  of 
  the 
  size 
  of 
  the 
  corallites 
  and 
  their 
  oblique 
  direction. 
  

  

  Of 
  the 
  fossils 
  of 
  the 
  later 
  rocks, 
  C. 
  delicatulus 
  runs 
  a 
  considerable 
  

   chance 
  of 
  being 
  confounded 
  with 
  Helopora 
  fragilis, 
  Hall, 
  which 
  it 
  

   much 
  resembles 
  superficially. 
  It 
  is, 
  however, 
  readily 
  distinguished 
  

   by 
  its 
  almost 
  always 
  being 
  branched, 
  by 
  the 
  form 
  of 
  the 
  calices, 
  and 
  

   by 
  the 
  fact 
  that 
  the 
  calices 
  are 
  not 
  arranged 
  between 
  longitudinal 
  

   elevated 
  lines. 
  

  

  Q. 
  J. 
  G. 
  S. 
  No. 
  120. 
  2 
  w 
  

  

  