﻿The 
  Fauna 
  of 
  the 
  Niagaka 
  Geoup. 
  129 
  

  

  proposed 
  Cytocrinus* 
  for 
  a 
  crinoid 
  of 
  precisely 
  the 
  same 
  

   structure 
  and 
  of 
  similar 
  form. 
  The 
  latter, 
  though 
  published 
  

   eight 
  years 
  later, 
  has 
  the 
  advantage 
  of 
  being 
  a 
  more 
  euphoni- 
  

   ous 
  name. 
  

  

  The' 
  genus 
  Ctenocrinus 
  of 
  Bronn, 
  as 
  described 
  by 
  Pictet, 
  

   possesses 
  a 
  structure 
  resembling, 
  or 
  identical 
  with, 
  Cytocri- 
  

   nus 
  and 
  Macrostylocrinus, 
  though 
  the 
  exterior 
  character 
  

   is 
  very 
  distinctive 
  ; 
  for 
  the 
  present 
  I 
  retain 
  the 
  latter 
  name. 
  

  

  Macrostylocrinus 
  striattjs. 
  

  

  Plate 
  13, 
  Figs. 
  1-4. 
  

  

  Macrostylocrinus 
  striatus 
  Hall. 
  Trans. 
  Alb. 
  Inst., 
  vol. 
  iv, 
  p. 
  207. 
  Abstract, 
  p. 
  13; 
  

   May, 
  1863. 
  

  

  Body 
  depressed 
  turbinate 
  : 
  calyx 
  to 
  the 
  summit 
  of 
  the 
  first 
  

   radials 
  hemispheric 
  in 
  form. 
  Rays 
  from 
  the 
  second 
  radials 
  

   spreading 
  ; 
  interradial 
  spaces 
  depressed 
  or 
  not 
  expanding 
  be- 
  

   yond 
  the 
  upper 
  edge 
  of 
  the 
  first 
  radial 
  plate 
  ; 
  basal 
  plates 
  

   comparatively 
  large 
  ; 
  first 
  radials 
  large, 
  prominent 
  in 
  the 
  mid- 
  

   dle 
  near 
  the 
  upper 
  margins; 
  second 
  radials 
  hexagonal, 
  not 
  

   half 
  as 
  large 
  as 
  the 
  first, 
  wider 
  than 
  high 
  ; 
  third 
  radials 
  smal- 
  

   ler 
  than 
  the 
  second, 
  pentagonal, 
  wider 
  than 
  high, 
  supporting 
  

   arm 
  plates 
  on 
  the 
  upper 
  sloping 
  sides 
  ; 
  first 
  interradials 
  larger 
  

   than 
  the 
  second 
  radials, 
  hexagonal, 
  supporting 
  two 
  plates 
  in 
  

   the 
  second 
  range. 
  

  

  Surface 
  finely 
  and 
  beautifully 
  striated 
  by 
  fine, 
  sharp, 
  undu- 
  

   lating 
  striae, 
  about 
  twelve 
  of 
  which 
  traverse 
  the 
  lower 
  side 
  of 
  

   the 
  first 
  radial 
  plate, 
  meeting 
  similar 
  ones 
  from 
  the 
  basal 
  

   plates 
  ; 
  the 
  apices 
  or 
  junction 
  of 
  the 
  striae 
  are 
  in 
  the 
  line 
  from 
  

   the 
  center 
  to 
  the 
  angles 
  of 
  the 
  plates 
  in 
  the 
  basal, 
  first 
  radial 
  

   and 
  interradial 
  plates, 
  while 
  on 
  the 
  surface 
  of 
  the 
  smaller 
  

   plates 
  these 
  lines 
  are 
  sometimes 
  broken 
  into 
  granules. 
  

  

  This 
  species 
  resembles 
  the 
  M. 
  ornatus 
  from 
  the 
  shale 
  of 
  the 
  

   Niagara 
  group 
  at 
  Lockport, 
  N. 
  Y. 
  ; 
  but 
  the 
  rays 
  are 
  more 
  

   spreading 
  and 
  the 
  surface 
  markings 
  are 
  finer. 
  

  

  Macrostylocrinus 
  striatus 
  var. 
  granulosus 
  n. 
  var. 
  

  

  Among 
  the 
  collections 
  fronijWaldron 
  there 
  is 
  another 
  species 
  

   of 
  this 
  genus, 
  or 
  a 
  constant 
  variety, 
  which 
  presents 
  a 
  uniformly 
  

   finely 
  granulose 
  surface. 
  The 
  prominent 
  short 
  ridge 
  from 
  the 
  

  

  * 
  Silurische 
  Fauna 
  des 
  Westlichen 
  Tennessee, 
  p. 
  4, 
  Tab. 
  4, 
  figs. 
  2 
  a, 
  2 
  b, 
  and 
  2 
  c. 
  

  

  15 
  

  

  