﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  I49 
  

  

  side 
  plates 
  pass 
  insensibly 
  into 
  the 
  plates 
  of 
  the 
  ventral 
  (upper) 
  side. 
  

   In 
  the 
  center 
  of 
  the 
  dorsal 
  side, 
  however, 
  a 
  regular 
  series 
  of 
  basal 
  

   plates 
  exists, 
  which 
  rest 
  on 
  the 
  stem 
  or 
  column. 
  

  

  The 
  mouth 
  is 
  indicated 
  by 
  a 
  central 
  or 
  subcentral 
  aperture 
  on 
  

   the 
  upper 
  (ventral) 
  surface, 
  and 
  is 
  sometimes 
  covered 
  by 
  smalt 
  

   plates. 
  From 
  it 
  radiate 
  from 
  two 
  to 
  five 
  simple 
  or 
  branching: 
  

   ambulacral 
  grooves, 
  which 
  are 
  also 
  frequently 
  roofed 
  over 
  by 
  plates. 
  

   The 
  anal 
  opening 
  is 
  situated 
  eccentrically 
  and 
  frequently 
  closed 
  by 
  

   a 
  valvular 
  pyramid. 
  

  

  The 
  calyx 
  plates 
  in 
  most 
  cystoids 
  are 
  perforated 
  by 
  pores 
  or 
  fis- 
  

   sures. 
  These 
  are 
  often 
  arranged 
  to 
  form 
  lozenge-shaped 
  or 
  rhombic 
  

   figures, 
  the 
  pore 
  rhombs, 
  which 
  are 
  disposed 
  one 
  half 
  on 
  each 
  of 
  two 
  

   adjoining 
  plates, 
  while 
  the 
  line 
  of 
  suture 
  between 
  the 
  plates 
  forms 
  

   either 
  the 
  longer 
  or 
  the 
  shorter 
  diagonal 
  of 
  the 
  rhomb. 
  The 
  

   pores 
  of 
  opposite 
  sides 
  of 
  the 
  rhomb 
  are 
  united 
  by 
  perfectly 
  closed, 
  

   straight 
  ducts, 
  which 
  pass 
  horizontally 
  across 
  the 
  line 
  of 
  suture, 
  

   and 
  produce 
  a 
  transversely 
  striated 
  appearance 
  ( 
  C 
  a 
  r 
  y 
  o 
  - 
  

   c 
  r 
  i 
  n 
  u 
  s 
  , 
  fig. 
  46). 
  These 
  striate 
  rhombs 
  are 
  generally 
  visible 
  only 
  

   in 
  weathered 
  specimens. 
  They 
  may 
  be 
  present 
  on 
  all 
  plates 
  or 
  only 
  

   on 
  a 
  few. 
  In 
  C 
  a 
  1 
  1 
  o 
  c 
  y 
  s 
  t 
  i 
  t 
  e 
  s 
  and 
  other 
  related 
  genera, 
  the 
  

   pore 
  rhombs 
  are 
  reduced 
  to 
  pectinated 
  rhombs, 
  which 
  are 
  few 
  in 
  

   number, 
  and 
  each 
  separated 
  into 
  two 
  distinct 
  parts, 
  lying 
  on 
  con- 
  

   tiguous 
  plates 
  (fig. 
  47). 
  These 
  structures 
  have 
  probably 
  a 
  respir- 
  

   atory 
  function. 
  

  

  The 
  arms 
  are 
  feebly 
  developed 
  in 
  the 
  cystoids 
  and 
  often 
  but 
  few 
  

   in 
  number. 
  They 
  are 
  simple, 
  consisting 
  of 
  a 
  single 
  (uniserial) 
  or 
  

   a 
  double 
  (biserial) 
  row 
  of 
  plates, 
  and 
  possess 
  a 
  ventral 
  groove, 
  

   protected 
  by 
  covering 
  plates. 
  

  

  Genus 
  caryocrinus 
  Say 
  

  

  [Ety. 
  : 
  xdpuo'^ 
  , 
  a 
  nut; 
  xphov^ 
  lily] 
  

  

  (1825. 
  Acad. 
  nat. 
  sci. 
  Phil. 
  Jour. 
  4:289) 
  

  

  Calyx 
  composed 
  of 
  a 
  moderate 
  number 
  of 
  plates 
  arranged 
  in 
  a 
  

   hexamerous 
  manner, 
  and 
  with 
  the 
  base 
  composed 
  of 
  two 
  cycles 
  

   of 
  plates 
  (dicyclic). 
  Lowest 
  (infrabasals) 
  four, 
  unequal; 
  followed 
  

   by 
  a 
  second 
  row 
  of 
  six 
  basals, 
  which 
  alternate 
  in 
  position 
  with 
  

   those 
  of 
  the 
  preceding 
  and 
  succeeding 
  cycles. 
  Third 
  cycle 
  of 
  eight 
  

   plates 
  of 
  which 
  six 
  are 
  regarded 
  as 
  radials, 
  the 
  others 
  as 
  interradials 
  

   (Carpenter). 
  Ventral 
  surface 
  formed 
  of 
  six 
  or 
  more 
  small 
  pieces. 
  

   All 
  plates 
  of 
  the 
  calyx 
  furnished 
  with 
  pore-rhombs; 
  the 
  summit 
  

   plates 
  without 
  perforations. 
  Mouth 
  and 
  ambulacral 
  grooves 
  below 
  

   the 
  ventral 
  plates 
  or 
  tegmen. 
  Anal 
  opening 
  protected 
  by 
  a 
  valvular 
  

   pyramid, 
  and 
  situated 
  on 
  the 
  outer 
  margin 
  of 
  the 
  ventral 
  surface. 
  

   Arms, 
  6 
  to 
  13 
  in 
  number, 
  situated 
  on 
  the 
  ventral 
  margin, 
  and 
  

   relatively 
  feeble. 
  Stem 
  long, 
  composed 
  of 
  cylindric 
  segments. 
  

  

  