﻿502 
  H. 
  ALLEYNE 
  NICHOLSON 
  ON 
  SPECIES 
  OP 
  CH.ETETES 
  

  

  with 
  moderately 
  thin 
  walls. 
  A 
  greater 
  or 
  less 
  number 
  of 
  smaller 
  

   calices, 
  usually 
  iu 
  the 
  form 
  of 
  very 
  minute 
  circular 
  tubuli, 
  situated 
  

   at 
  the 
  angles 
  of 
  the 
  larger 
  corallites. 
  Surface 
  covered 
  with 
  conical, 
  

   rarely 
  transversely 
  elongated 
  eminences 
  or 
  tubercles, 
  which 
  some- 
  

   times 
  attain 
  a 
  height 
  of 
  over 
  half 
  a 
  line, 
  and 
  which 
  are 
  placed 
  at 
  

   intervals 
  of 
  from 
  half 
  a 
  line 
  to 
  nearly 
  1 
  line 
  apart. 
  These 
  tubercles 
  

   are 
  covered 
  with 
  corallites 
  which 
  are 
  not 
  larger 
  than 
  the 
  average 
  ; 
  

   and 
  their 
  summits 
  may 
  be 
  partially 
  compact 
  or 
  furnished 
  with 
  

   corallites 
  of 
  smaller 
  size 
  than 
  usual. 
  

  

  At 
  least 
  two 
  variations 
  appear 
  to 
  be 
  included 
  under 
  this 
  species. 
  

   In 
  some 
  forms, 
  which 
  may 
  probably 
  be 
  regarded 
  as 
  the 
  most 
  typical, 
  

   the 
  eminences 
  of 
  the 
  surface 
  are 
  very 
  prominent, 
  and 
  the 
  normal 
  or 
  

   average 
  corallites 
  are 
  separated 
  by 
  a 
  great 
  number 
  of 
  extraordinarily 
  

   minute 
  cylindrical 
  corallites, 
  which 
  vary 
  from 
  three 
  to 
  six 
  or 
  more 
  

   placed 
  round 
  each 
  of 
  the 
  larger 
  tubes, 
  which 
  thus 
  acquire 
  a 
  more 
  or 
  

   less 
  circular 
  form. 
  In 
  another 
  variety 
  the 
  surface-tubercles 
  are 
  

   usually 
  not 
  so 
  pronounced, 
  and 
  the 
  corallites 
  are 
  for 
  the 
  most 
  part 
  

   nearly 
  equal 
  in 
  size. 
  Even 
  in 
  these 
  examples, 
  however, 
  there 
  are 
  

   occasional 
  excessively 
  minute 
  corallites 
  at 
  the 
  points 
  where 
  the 
  

   larger 
  ones 
  meet, 
  though 
  this 
  is 
  never 
  a 
  conspicuous 
  feature 
  as 
  it 
  is 
  

   in 
  the 
  preceding 
  variety. 
  

  

  Locality 
  and 
  Formation. 
  Common 
  in 
  the 
  Cincinnati 
  group 
  (Hud- 
  

   son-River 
  formation), 
  near 
  Cincinnati, 
  Ohio. 
  

  

  2. 
  Ch^texes 
  RTTGosrrs, 
  Edw. 
  & 
  H. 
  PI. 
  XXIX. 
  fig. 
  2. 
  

  

  Chcetetes 
  rugosus, 
  Edwards 
  & 
  Haime, 
  Pol. 
  Foss. 
  des 
  Terr. 
  Pal. 
  

   pi. 
  20. 
  fig. 
  6. 
  

  

  Branches 
  cylindrical 
  or 
  flattened, 
  from 
  2 
  to 
  3 
  lines 
  in 
  diameter, 
  

   dividing 
  dichotomously 
  at 
  short 
  intervals. 
  Corallites 
  polygonal 
  or 
  

   subcircular, 
  the 
  average 
  ones 
  about 
  six 
  or 
  eight 
  in 
  the 
  space 
  of 
  1 
  fine, 
  

   separated 
  by 
  numerous 
  exceedingly 
  minute 
  circular 
  tubes. 
  Surface 
  

   exhibiting 
  numerous 
  elevations, 
  which 
  have 
  a 
  height 
  of 
  from 
  one 
  

   quarter 
  of 
  a 
  line 
  to 
  half 
  a 
  line, 
  and 
  are 
  transversely 
  elongated, 
  so 
  as 
  

   to 
  constitute 
  so 
  many 
  discontinuous 
  transverse 
  ridges. 
  These 
  ridges 
  

   vary 
  in 
  length, 
  but 
  they 
  do 
  not 
  extend 
  round 
  the 
  stems, 
  and 
  they 
  

   are 
  usually 
  sharp-edged 
  and 
  placed 
  about 
  half 
  a 
  line 
  apart. 
  The 
  

   corallites 
  on 
  the 
  ridges 
  are 
  not 
  larger 
  than 
  those 
  on 
  the 
  other 
  parts 
  

   of 
  the 
  coral. 
  

  

  This 
  species 
  differs 
  from 
  C. 
  Dalei 
  in 
  little 
  except 
  in 
  the 
  fact 
  that 
  

   the 
  tubercles 
  are 
  elongated 
  in 
  a 
  direction 
  at 
  right 
  angles 
  to 
  the 
  axis 
  

   of 
  the 
  branches. 
  It 
  may 
  be 
  only 
  a 
  pronounced 
  variety 
  of 
  C. 
  Dalei. 
  

  

  Locality 
  and 
  Formation. 
  Common 
  in 
  the 
  Cincinnati 
  group, 
  near 
  

   Cincinnati, 
  Ohio. 
  

  

  3. 
  Ch-zeteies 
  appkoximattts, 
  Nich. 
  PI. 
  XXIX. 
  figs. 
  3, 
  3 
  a. 
  

   Corallum 
  consisting 
  of 
  cylindrical 
  stems, 
  dividing 
  dichotomously, 
  

  

  and 
  having 
  a 
  diameter 
  of 
  about 
  2 
  or 
  2| 
  lines. 
  Corallites 
  thick- 
  

   walled, 
  though 
  not 
  excessively 
  so, 
  subcircular 
  or 
  polygonal, 
  eight 
  or 
  

   ten 
  in 
  the 
  space 
  of 
  1 
  line, 
  sometimes 
  with 
  excessively 
  minute 
  coral- 
  

   lites 
  interspersed 
  amongst 
  the 
  larger 
  ones, 
  though 
  these 
  are 
  never 
  

  

  