﻿PROM 
  THE 
  LOWER 
  SILURIAN 
  OF 
  NORTH 
  AMERICA. 
  513 
  

  

  to 
  be 
  solid 
  throughout 
  ; 
  but 
  in 
  other 
  cases 
  they 
  are 
  elevated, 
  and 
  

   carry 
  corallites 
  of 
  the 
  ordinary 
  size 
  ou 
  their 
  lateral 
  aspects. 
  

  

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

  

  19. 
  Chjetetes 
  Ortoni, 
  Mch. 
  PL 
  XXTX. 
  figs. 
  15-15 
  b. 
  

  

  Corallum 
  forming 
  exceedingly 
  thin 
  crusts, 
  not 
  more 
  than 
  from 
  

   one 
  sixth 
  to 
  one 
  eighth 
  of 
  a 
  line 
  in 
  thickness, 
  attached 
  parasitically 
  

   to 
  submarine 
  objects. 
  Crusts 
  usually 
  constituting 
  small 
  circular 
  

   expansions, 
  or 
  irregular 
  and 
  indefinite 
  in 
  form. 
  Surface 
  exhibit- 
  

   ing 
  numerous, 
  minute, 
  rounded 
  or 
  obtusely 
  conical 
  eminences, 
  

   which 
  are 
  placed 
  at 
  intervals 
  apart 
  of 
  half 
  a 
  line, 
  more 
  or 
  less. 
  The 
  

   tubercles 
  are 
  somewhat 
  compact 
  at 
  their 
  summits, 
  and 
  carry 
  upon 
  

   their 
  sides 
  corallites 
  which 
  are 
  little 
  or 
  not 
  at 
  all 
  larger 
  than 
  tbe 
  

   average. 
  The 
  corallites 
  are 
  somewhat 
  oblique 
  to 
  the 
  surface, 
  mode- 
  

   rately 
  thick-walled, 
  subequal, 
  without 
  any 
  minute 
  intercalated 
  

   tubuli. 
  Calices 
  small, 
  subpolygonal 
  or 
  oval, 
  from 
  ten 
  to 
  twelve 
  in 
  

   the 
  space 
  of 
  one 
  line 
  ; 
  their 
  margins 
  thick 
  and 
  surmounted 
  by 
  minute 
  

   and 
  crowded 
  miliary 
  granules, 
  which 
  are 
  rounded 
  and 
  not 
  spinous, 
  

   and 
  which 
  are 
  placed 
  almost 
  in 
  contact 
  with 
  one 
  another. 
  

  

  In 
  appearance, 
  this 
  species, 
  but 
  for 
  its 
  extreme 
  thinness, 
  and 
  the 
  

   small 
  close-set 
  surface- 
  tubercles, 
  might 
  be 
  confounded 
  with 
  C. 
  pa- 
  

   pillatus. 
  On 
  examination 
  with 
  a 
  high 
  power, 
  however, 
  it 
  is 
  readily 
  

   distinguished 
  from 
  all 
  the 
  known 
  incrusting 
  species 
  of 
  Chcetetes 
  by 
  

   the 
  fine 
  and 
  close 
  granulation 
  of 
  the 
  margins 
  of 
  the 
  calices, 
  giving 
  

   to 
  the 
  surface 
  quite 
  a 
  peculiar 
  appearance. 
  All 
  the 
  specimens 
  I 
  

   have 
  seen 
  of 
  this 
  singular 
  species 
  are 
  parasitic 
  upon 
  Strophomena 
  

   alternata 
  ; 
  and 
  I 
  am 
  informed 
  by 
  Mr. 
  James 
  that 
  it 
  is 
  rarely 
  found 
  

   attached 
  to 
  any 
  thing 
  else. 
  In 
  spite 
  of 
  the 
  granulated 
  margins 
  of 
  

   the 
  calices, 
  it 
  appears 
  to 
  be 
  a 
  genuine 
  Chcetetes, 
  and 
  I 
  see 
  no 
  reason 
  

   for 
  removing 
  it 
  from 
  this 
  genus. 
  

  

  I 
  have 
  named 
  the 
  species 
  after 
  my 
  friend 
  Prof. 
  Edward 
  Orton, 
  of 
  

   the 
  Geological 
  Survey 
  of 
  Ohio, 
  from 
  whom, 
  as 
  well 
  as 
  from 
  Mr. 
  

   U. 
  P. 
  James, 
  I 
  have 
  received 
  the 
  specimens 
  from 
  which 
  the 
  above 
  

   description 
  is 
  drawn. 
  

  

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

  

  EXPLANATION 
  OF 
  THE 
  PLATES. 
  

  

  Plate 
  XXIX. 
  

  

  Fig. 
  1 
  . 
  Fragment 
  of 
  Chcetetes 
  Dalei, 
  Edw. 
  & 
  H., 
  of 
  the 
  natural 
  size. 
  (In 
  this, 
  

   as 
  in 
  all 
  the 
  following 
  figures 
  of 
  Chcetetes 
  which 
  are 
  not 
  enlarged, 
  

   the 
  calices 
  have 
  been 
  omitted 
  for 
  the 
  sake 
  of 
  clearness, 
  and 
  only 
  the 
  

   general 
  form 
  of 
  the 
  corallum 
  is 
  shown, 
  together 
  with 
  any 
  superficial 
  

   prominences 
  which 
  may 
  be 
  present.) 
  

   la. 
  A 
  portion 
  of 
  the 
  preceding, 
  enlarged, 
  showing 
  the 
  very 
  minute 
  inter- 
  

   mediate 
  tubuli. 
  

  

  2. 
  Fragment 
  of 
  Chcetetes 
  rugosus, 
  Edw. 
  & 
  H., 
  of 
  the 
  natural 
  size. 
  

  

  3. 
  Fragment 
  of 
  Chcetetes 
  approximates, 
  Nich., 
  of 
  the 
  natural 
  size, 
  showing 
  

  

  the 
  small 
  tubercles. 
  

   3 
  a. 
  A 
  portion 
  of 
  the 
  preceding, 
  enlarged, 
  showing 
  a 
  surface-tubercle 
  and 
  

   very 
  minute 
  tubuli 
  between 
  the 
  average 
  corallites. 
  Few 
  specimens, 
  

   however, 
  exhibit 
  as 
  many 
  of 
  these 
  intermediate 
  tubuli. 
  

  

  