﻿506 
  H. 
  ALLETNE 
  NICHOLSON 
  ON 
  SPECIES 
  OE 
  CH^TETES 
  

  

  Locality 
  and 
  Formation. 
  Common 
  in 
  the 
  Hudson-River 
  group 
  of 
  

   Canada 
  aimost 
  everywhere 
  ; 
  also 
  in 
  the 
  Cincinnati 
  group, 
  near 
  Cin- 
  

   cinnati 
  ; 
  also 
  in 
  the 
  Trenton 
  Limestone. 
  

  

  9. 
  Ch^tetes 
  ? 
  nodtjlostjs, 
  Nich. 
  PL 
  XXIX. 
  figs. 
  9, 
  9 
  a. 
  

  

  Corallum 
  dendroid, 
  minute, 
  of 
  small 
  cylindrical 
  stems, 
  which 
  

   hranch 
  dichotomously 
  at 
  intervals 
  of 
  2 
  lines, 
  and 
  have 
  a 
  diameter 
  of 
  

   from 
  two 
  thirds 
  of 
  a 
  line 
  to 
  1 
  line. 
  Corallites 
  prismatic 
  or 
  hexa- 
  

   gonal, 
  directed 
  somewhat 
  obliquely 
  to 
  the 
  surface, 
  of 
  two 
  sizes. 
  

   Larger 
  corallites 
  opening 
  by 
  subcircular 
  or 
  oval 
  apertures, 
  the 
  long 
  

   diameter 
  of 
  which 
  coincides 
  with 
  the 
  axis 
  of 
  the 
  stems 
  ; 
  from 
  six 
  to 
  

   eight 
  in 
  the 
  space 
  of 
  1 
  line 
  measured 
  vertically. 
  Smaller 
  corallites 
  

   in 
  the 
  form 
  of 
  exceedingly 
  minute 
  circular 
  tubuli 
  interspersed 
  

   amongst 
  the 
  larger 
  tubes. 
  Surface 
  exhibiting 
  numerous 
  minute, 
  

   sometimes 
  conical, 
  sometimes 
  transversely 
  elongated 
  elevations 
  or 
  

   tubercles, 
  which 
  are 
  placed 
  at 
  distances 
  of 
  about 
  half 
  a 
  line 
  apart, 
  

   and 
  give 
  to 
  the 
  surface 
  a 
  characteristic 
  nodulose 
  appearance. 
  

  

  This 
  very 
  distinct 
  species 
  is 
  more 
  nearly 
  allied 
  to 
  C. 
  Dalei 
  than 
  

   to 
  any 
  other 
  ; 
  but 
  it 
  is 
  very 
  readily 
  separated 
  by 
  its 
  much 
  more 
  

   slender 
  and 
  graceful 
  proportions, 
  and 
  the 
  much 
  smaller 
  size 
  of 
  the 
  

   proportionally 
  remote 
  tubercles. 
  One 
  specimen, 
  indeed, 
  which 
  can 
  

   hardly 
  be 
  referred 
  elsewhere, 
  exhibits 
  on 
  transverse 
  section 
  about 
  

   twelve 
  very 
  distinct 
  radiating 
  septa 
  meeting 
  in 
  the 
  centre 
  of 
  the 
  

   corallites. 
  Though 
  all 
  the 
  other 
  examples 
  possess 
  tabulae 
  and 
  have 
  

   all 
  the 
  characters 
  of 
  Chcetetes, 
  this 
  raises 
  the 
  suspicion 
  that 
  possibly 
  

   the 
  form 
  may 
  require, 
  on 
  more 
  extended 
  investigation, 
  to 
  be 
  removed 
  

   from 
  Chmtetes. 
  

  

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

   ' 
  Collected 
  by 
  Mr. 
  TJ. 
  P. 
  James. 
  

  

  10. 
  CHiETETEs 
  Jamesi, 
  Nich. 
  PI. 
  XXIX. 
  figs. 
  10-10 
  b. 
  

  

  Corallum 
  of 
  cylindrical 
  or 
  subcylindrical 
  hollow 
  branches, 
  the 
  

   diameter 
  of 
  which 
  is 
  from 
  3 
  to 
  5 
  lines 
  ; 
  or 
  of 
  somewhat 
  lobate 
  and 
  

   subpalmate 
  masses, 
  the 
  extremities 
  of 
  which 
  are 
  rounded. 
  Branches 
  

   in 
  the 
  ramose 
  forms 
  dividing 
  dichotomously 
  at 
  irregular 
  intervals, 
  

   irregularly 
  thickened 
  and 
  nodulose. 
  Corallites 
  oval 
  or 
  circular 
  in 
  

   section, 
  of 
  unequal 
  sizes. 
  The 
  larger 
  corallites 
  about 
  six 
  in 
  the 
  

   space 
  of 
  1 
  line, 
  with 
  very 
  thick 
  walls, 
  the 
  margins 
  of 
  the 
  round 
  or 
  

   subpolygonal 
  calices 
  being 
  obscurely 
  tuberculated 
  or 
  granulated. 
  

   The 
  larger 
  corallites 
  are 
  separated 
  by 
  extremely 
  minute 
  cylindrical 
  

   tubuli, 
  the 
  number 
  of 
  which 
  varies 
  in 
  different 
  parts 
  of 
  the 
  corallum. 
  

   The 
  surface 
  exhibits 
  no 
  eminences 
  or 
  tubercles, 
  or 
  groups 
  of 
  large- 
  

   sized 
  corallites 
  ; 
  but 
  typical 
  specimens 
  exhibit 
  at 
  irregular 
  intervals 
  

   stellate 
  spaces, 
  which 
  are 
  either 
  solid 
  or 
  minutely 
  punctate, 
  and 
  have 
  

   a 
  diameter 
  of 
  two 
  thirds 
  of 
  a 
  line. 
  

  

  This 
  species 
  is 
  related 
  to 
  Chaitetes 
  tumiclus, 
  Phill., 
  of 
  the 
  Car- 
  

   boniferous 
  rocks, 
  especially 
  in 
  the 
  rounded, 
  thick-walled 
  corallites, 
  

   separated 
  by 
  minute 
  intermediate 
  tubes. 
  I 
  have, 
  however, 
  com- 
  

   pared 
  it 
  with 
  specimens 
  of 
  the 
  latter, 
  and 
  find 
  it 
  to 
  be 
  clearly 
  di- 
  

   stinguished 
  by 
  the 
  larger 
  size 
  and 
  much 
  thicker 
  walls 
  of 
  the 
  corallites, 
  

  

  