﻿504 
  H. 
  ALLEYNE 
  NICHOLSON 
  ON 
  SPECIES 
  OE 
  CH^TETES 
  

  

  and 
  they 
  are 
  placed 
  about 
  1 
  line 
  apart 
  ; 
  they 
  are 
  very 
  slightly 
  or 
  

   not 
  at 
  all 
  elevated 
  above 
  the 
  general 
  surface, 
  so 
  that 
  there 
  are 
  no 
  

   conspicuous 
  tubercles. 
  

  

  The 
  characters 
  of 
  this 
  species 
  are 
  so 
  well 
  marked 
  as 
  to 
  render 
  its 
  

   recognition 
  very 
  easy, 
  even 
  in 
  small 
  fragments. 
  

  

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

  

  6. 
  CHiETETEs 
  Fletcheri, 
  Edw. 
  & 
  H. 
  PL 
  XXIX. 
  figs. 
  6, 
  6 
  a. 
  

   Chcetetes 
  Fletcheri, 
  Edwards 
  & 
  Haime, 
  Pol. 
  Foss. 
  des 
  Terr. 
  Pale'oz. 
  

  

  p. 
  271. 
  

  

  Chcetetes 
  lycoperdon, 
  Hall 
  (ex 
  parte), 
  Pal. 
  N. 
  Y. 
  vol. 
  ii. 
  pi. 
  17. 
  figs. 
  

   Ig-i 
  (cset. 
  excl.) 
  ; 
  also 
  Pal. 
  K. 
  Y. 
  vol. 
  i. 
  pi. 
  24. 
  fig. 
  \g 
  (cast, 
  excl.)? 
  

  

  Monticulipora 
  Fletcheri, 
  Edw. 
  & 
  Haime, 
  Brit. 
  Foss. 
  Corals, 
  pi. 
  62. 
  

   figs. 
  3, 
  3 
  a. 
  

  

  Corallum 
  ramose, 
  branches 
  from 
  1| 
  to 
  3 
  lines 
  in 
  diameter, 
  

   cylindrical 
  or 
  subcylindrical, 
  often 
  irregularly 
  swollen 
  at 
  intervals, 
  

   dividing 
  dichotomously 
  usually 
  at 
  considerable 
  intervals. 
  Corallites 
  

   with 
  moderately 
  thick 
  walls, 
  the 
  average 
  ones 
  of 
  unequal 
  sizes, 
  

   about 
  eight 
  in 
  the 
  space 
  of 
  1 
  line, 
  and 
  having 
  very 
  minute 
  tubuli 
  

   sparingly 
  interspersed 
  amongst 
  them. 
  Surface 
  smooth, 
  destitute 
  of 
  

   tubercles, 
  but 
  occasionally 
  showing 
  groups 
  of 
  corallites 
  which 
  are 
  

   very 
  slightly 
  larger 
  than 
  the 
  average. 
  

  

  The 
  examples 
  of 
  this 
  species 
  which 
  I 
  possess 
  from 
  the 
  Clinton 
  

   group 
  (Upper 
  Silurian) 
  agree 
  entirely 
  with 
  the 
  description 
  given 
  by 
  

   Edwards 
  and 
  Haime, 
  being 
  smooth, 
  and 
  simply 
  having 
  a 
  moderate 
  

   number 
  of 
  very 
  minute 
  tubes 
  irregularly 
  intercalated 
  amongst 
  the 
  

   ordinary 
  corallites, 
  these 
  latter 
  varying 
  slightly 
  in 
  their 
  dimensions. 
  

   On 
  the 
  other 
  hand, 
  the 
  Lower-Silurian 
  examples 
  which 
  I 
  have 
  

   referred 
  to 
  this 
  species, 
  though 
  also 
  smooth, 
  and 
  also 
  having 
  minute 
  

   tubuli 
  sparsely 
  interspersed 
  amongst 
  the 
  larger 
  corallites, 
  exhibit 
  

   distinct 
  groups 
  of 
  corallites 
  which 
  are 
  of 
  rather 
  larger 
  size 
  than 
  the 
  

   average, 
  and 
  which 
  are 
  not 
  set 
  upon 
  distinct 
  elevations. 
  They 
  thus 
  

   approach 
  0. 
  pulchellus, 
  from 
  which 
  they 
  are 
  hardly 
  distinguishable 
  

   except 
  by 
  the 
  fact 
  that 
  the 
  groups 
  of 
  large-sized 
  corallites 
  are 
  not 
  

   nearly 
  so 
  conspicuous, 
  the 
  individual 
  corallites 
  which 
  compose 
  them 
  

   being 
  only 
  very 
  slightly 
  above 
  the 
  average 
  size. 
  On 
  the 
  contrary, 
  

   in 
  C. 
  pidchellus 
  the 
  groups 
  of 
  large-sized 
  corallites 
  are 
  very 
  con- 
  

   spicuous, 
  as 
  the 
  corallites 
  composing 
  them 
  are 
  nearly 
  or 
  quite 
  twice 
  

   as 
  large 
  as 
  the 
  ordinary 
  ones. 
  Perhaps 
  the 
  Lower-Silurian 
  forms 
  

   here 
  regarded 
  as 
  referable 
  to 
  C. 
  Fletcheri 
  may 
  constitute 
  a 
  distinct 
  

   variety 
  either 
  of 
  this 
  or 
  of 
  C. 
  pvlchellus. 
  

  

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

   the 
  Province 
  of 
  Ontario, 
  and 
  in 
  the 
  Cincinnati 
  group, 
  near 
  Cincinnati, 
  

   Ohio 
  ; 
  also 
  in 
  the 
  Clinton 
  group 
  (Upper 
  Silurian) 
  at 
  Dundas, 
  Ontario. 
  

  

  7. 
  CHiETETES 
  gracilis, 
  Janies. 
  PL 
  XXIX. 
  figs. 
  7, 
  7 
  a. 
  

  

  GJiostetes 
  gracilis, 
  James, 
  Catalogue 
  of 
  the 
  Fossils 
  of 
  the 
  Cincinnati 
  

   Group, 
  1871 
  (named, 
  but 
  not 
  figured 
  or 
  described). 
  

  

  Corallum 
  dendroid, 
  the 
  branches 
  cylindrical 
  or 
  subcylindrical, 
  

   from 
  less 
  than 
  1 
  line 
  to 
  2 
  lines 
  or 
  more 
  in 
  diameter, 
  dividing 
  dicho- 
  

  

  