﻿512 
  H. 
  ALLEYNE 
  NICHOLSON 
  ON 
  SPECIES 
  OE 
  CHjETETES 
  

  

  17. 
  Ciuetetes 
  papillatus, 
  M'Coy. 
  PI. 
  XXIX. 
  figs. 
  12-12 
  b. 
  

  

  Nebulipora 
  papillata, 
  M'Coy, 
  Brit. 
  Pal. 
  Poss. 
  p. 
  24, 
  pi. 
  1 
  C. 
  fig. 
  5. 
  

  

  Chcetetes 
  tuberculatus, 
  Edw. 
  & 
  Haime, 
  Pol. 
  Poss. 
  des 
  Terr. 
  Paleoz. 
  

   pi. 
  19. 
  figs. 
  3, 
  3 
  a. 
  

  

  Monticulipora 
  papillata, 
  Edw. 
  & 
  Haime, 
  Brit. 
  Poss. 
  Corals, 
  pi. 
  

   62. 
  figs. 
  4, 
  4 
  a. 
  

  

  Corallum 
  forming 
  an 
  exceedingly 
  thin 
  crust, 
  usually 
  not 
  more 
  

   than 
  half 
  a 
  line 
  in 
  thickness, 
  growing 
  upon 
  Bra-chiopods 
  and 
  other 
  

   foreign 
  objects. 
  Surface 
  exhibiting 
  rounded 
  tuberosities, 
  sometimes 
  

   Very 
  slightly 
  elevated, 
  placed 
  about 
  their 
  own 
  diameter 
  apart, 
  and 
  

   occupied 
  by 
  corallites 
  of 
  a 
  larger 
  size 
  than 
  the 
  average. 
  Corallites 
  

   polygonal, 
  thiu-walled, 
  somewhat 
  variable 
  in 
  size, 
  not 
  having 
  very 
  

   minute 
  tubuli 
  interspersed 
  amongst 
  them. 
  About 
  eight 
  or 
  ten 
  of 
  

   the 
  average 
  corallites 
  in 
  the 
  space 
  of 
  one 
  line. 
  Width 
  of 
  the 
  

   tubercles 
  one 
  line 
  or 
  a 
  little 
  more. 
  

  

  Our 
  specimens 
  agree 
  well 
  with 
  the 
  description 
  given 
  by 
  Mr. 
  M'Coy 
  

   of 
  Nebulipora 
  papillata 
  ; 
  but 
  they 
  differ 
  somewhat 
  from 
  that 
  given 
  

   by 
  Edwards 
  & 
  Haime. 
  Thus 
  the 
  tubercles 
  in 
  our 
  examples 
  are 
  

   rounded, 
  not 
  to 
  any 
  marked 
  extent 
  elongated 
  or 
  compressed 
  ; 
  and 
  

   the 
  large 
  corallites 
  occupying 
  these 
  eminences 
  are 
  from 
  five 
  to 
  six 
  

   in 
  one 
  line 
  (instead 
  of 
  being 
  one-third 
  of 
  a 
  line 
  in 
  width). 
  

  

  The 
  tubercles 
  are 
  not 
  uncommonly 
  perforated 
  by 
  regular 
  and 
  

   large 
  circular 
  perforations, 
  which 
  have 
  a 
  diameter 
  of 
  about 
  half 
  a 
  

   line, 
  and 
  appear 
  to 
  be 
  the 
  mouths 
  of 
  vertical 
  tubes. 
  I 
  have, 
  how- 
  

   ever, 
  noticed 
  similar 
  perforations 
  in 
  several 
  other 
  species 
  of 
  Chaitetes 
  ; 
  

   and 
  they 
  are 
  probably 
  extraneous 
  to 
  the 
  coral 
  itself. 
  

  

  Locality 
  and 
  Formation. 
  Cincinnati 
  group, 
  near 
  Cincinnati, 
  

   Ohio. 
  

  

  18. 
  Ch^tetes 
  corticans, 
  Nich. 
  PL 
  XXIX. 
  figs. 
  13, 
  13 
  a, 
  14. 
  

  

  Corallum 
  forming 
  a 
  thin 
  crust, 
  growing 
  parasitically 
  upon 
  foreign 
  

   bodies, 
  and 
  having 
  a 
  thickness 
  of 
  less 
  than 
  one 
  quarter 
  of 
  a 
  line, 
  or, 
  

   when 
  in 
  superimposed 
  layers, 
  attaining 
  a 
  thickness 
  of 
  half 
  a 
  line. 
  

   Surface 
  exhibiting 
  a 
  number 
  of 
  long, 
  narrow, 
  compressed 
  tubercles, 
  

   which 
  are 
  all 
  drawn 
  out 
  in 
  one 
  direction, 
  and 
  which, 
  whilst 
  carry- 
  

   ing 
  average-sized 
  corallites 
  on 
  their 
  sides, 
  appear 
  to 
  be 
  compact 
  at 
  

   their 
  summits. 
  The 
  long 
  diameter 
  of 
  these 
  tubercles 
  varies 
  from 
  

   two 
  thirds 
  of 
  a 
  line 
  to 
  two 
  lines, 
  their 
  width 
  not 
  exceeding 
  half 
  a 
  

   line, 
  and 
  their 
  height 
  being 
  variable. 
  They 
  are 
  arranged 
  in 
  irre- 
  

   gularly 
  diagonal 
  lines, 
  and 
  are 
  placed 
  at 
  intervals 
  apart 
  of 
  from 
  

   half 
  a 
  line 
  to 
  two 
  thirds 
  of 
  a 
  line. 
  The 
  corallites 
  are 
  thin-walled, 
  

   polygonal, 
  subequal, 
  from 
  eight 
  to 
  ten 
  in 
  the 
  space 
  of 
  one 
  line, 
  

   without 
  any 
  intermediate 
  minute 
  tubuli. 
  There 
  are 
  also 
  no 
  groups 
  

   of 
  large-sized 
  corallites. 
  

  

  This 
  species 
  is 
  allied 
  to 
  C. 
  papillatus, 
  M'Coy, 
  but 
  appears 
  to 
  be 
  

   sufficiently 
  distinguished 
  by 
  the 
  long, 
  narrow 
  tubercles, 
  which 
  do 
  

   not 
  carry 
  any 
  large-sized 
  corallites. 
  The 
  specimens 
  which 
  I 
  have 
  

   seen 
  are 
  found 
  coating 
  Orthocerata, 
  and 
  forming 
  thin 
  but 
  extended 
  

   crusts. 
  In 
  some 
  examples 
  the 
  tubercles 
  are 
  depressed, 
  and 
  appear 
  

  

  