﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  1 
  53 
  

  

  An 
  anal 
  interradius 
  is 
  present 
  in 
  unsymmetric 
  forms. 
  The 
  tcgmen 
  

   forms 
  the 
  cover, 
  or 
  ventral 
  part 
  of 
  the 
  calyx, 
  and 
  is 
  composed 
  of 
  

   plates 
  either 
  closely 
  ankylosed, 
  or 
  held 
  together 
  by 
  a 
  leathery 
  

   membrane. 
  In 
  the 
  Paleozoic 
  Camerata 
  the 
  plates 
  of 
  the 
  ventral 
  

   disk 
  fit 
  closely 
  and 
  they 
  are 
  considerably 
  thickened, 
  forming 
  a 
  very 
  

   rigid, 
  more 
  or 
  less 
  convex 
  vault, 
  from 
  which 
  may 
  rise 
  the 
  plated 
  

   anal 
  proboscis. 
  

  

  The 
  mouth 
  of 
  Paleozoic 
  camerate 
  crinoids 
  lies 
  beneath 
  the 
  teg- 
  

   men, 
  the 
  only 
  external 
  opening 
  being 
  that 
  of 
  the 
  anus. 
  From 
  the 
  

   mouth, 
  radiating 
  grooves 
  or 
  canals 
  commonly 
  pass 
  outward 
  to 
  the 
  

   arms, 
  in 
  which 
  they 
  are 
  continued. 
  These 
  are 
  the 
  ambulacral 
  

   grooves, 
  along 
  which 
  the 
  food, 
  caught 
  on 
  the 
  arms, 
  is 
  conveyed 
  

   to 
  the 
  central 
  mouth. 
  These 
  grooves 
  may 
  be 
  open 
  or 
  covered 
  by 
  

   plates. 
  Within 
  the 
  cavity 
  of 
  the 
  calyx 
  are 
  the 
  viscera. 
  

  

  The 
  stalk, 
  or 
  stem, 
  is 
  composed 
  of 
  a 
  varying 
  number 
  of 
  joints, 
  

   which 
  are 
  circular, 
  elliptic 
  or 
  angular 
  in 
  cross-section 
  (fig. 
  52). 
  

   The 
  joint 
  nearest 
  to 
  the 
  calyx 
  is 
  the 
  last 
  formed 
  except 
  in 
  the 
  

   Flexibilia. 
  Frequently 
  a 
  certain 
  number 
  of 
  the 
  joints 
  bear 
  root- 
  

   like 
  extensions 
  or 
  cirri. 
  The 
  stem 
  and 
  cirri 
  are 
  pierced 
  by 
  an 
  axial 
  

   canal, 
  round 
  or 
  pentagonal 
  in 
  cross-section. 
  The 
  stem 
  was 
  in 
  most 
  

   cases 
  attached 
  by 
  a 
  root. 
  Some 
  crinoids 
  were 
  without 
  a 
  stem, 
  hav- 
  

   ing 
  been 
  attached 
  by 
  the 
  base 
  directly 
  or 
  more 
  rarely 
  being 
  free- 
  

   swimming: 
  orsranisms. 
  

  

  Order 
  larvifor^ii^ 
  Wachsmuth 
  & 
  Springer 
  

   Genus 
  stephanocrinus 
  Conrad 
  

   [Ety. 
  (T~i(pavo'^, 
  a 
  crown; 
  y.(>vMv>, 
  a 
  lily] 
  

   (1842. 
  Acad. 
  iiaf. 
  sci. 
  Phil. 
  Jour. 
  8:278) 
  

  

  Calyx 
  cup-shaped, 
  composed 
  of 
  three 
  elongate 
  basals, 
  five 
  radials, 
  

   and 
  five 
  interradials. 
  Radials 
  deeply 
  forked; 
  the 
  prongs 
  formed 
  by 
  

   the 
  margins 
  of 
  two 
  continuous 
  radials 
  extending 
  upward 
  between 
  

   the 
  arms, 
  and 
  building, 
  together 
  with 
  the 
  interradials, 
  a 
  row 
  of 
  five 
  

   pyramids, 
  near 
  the 
  summit 
  of 
  one 
  of 
  which 
  is 
  situated 
  the 
  anal 
  

   aperture. 
  Radial 
  incisions 
  occupied 
  by 
  the 
  ambulacral 
  grooves, 
  

   which 
  are 
  roofed 
  over 
  by 
  two 
  rows 
  of 
  covering 
  pieces; 
  those 
  of 
  the 
  

   same 
  row 
  closely 
  ankylosed. 
  First 
  costals 
  semilunate, 
  and 
  resting 
  

   within 
  a 
  horseshoe-like 
  concavity 
  near 
  the 
  outer 
  end 
  of 
  the 
  radial 
  

   incisions. 
  Tegmen 
  constituted 
  of 
  five 
  large 
  triangular 
  oral 
  plates. 
  

   Arms 
  very 
  short,^ 
  composed 
  of 
  about 
  10 
  pieces, 
  all 
  of 
  which 
  are 
  

   axillary 
  and 
  give 
  off 
  side 
  arms. 
  The 
  latter 
  are 
  biserial, 
  non-pinnu- 
  

  

  ^ 
  Generally 
  wanting 
  in 
  the 
  weathered-out 
  specimens. 
  

  

  