﻿156 
  

  

  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  terradial 
  plates. 
  Lower 
  brachials 
  forming 
  a 
  part 
  of 
  the 
  calyx; 
  cost.^ 
  

   hexagonal, 
  cost.^ 
  pentagonal, 
  axillary 
  bearing 
  the 
  distichals. 
  In- 
  

   terradials 
  lying 
  chiefly 
  between 
  the 
  costals. 
  Arms 
  lo 
  to 
  20, 
  biserial. 
  

   Stem 
  round. 
  

  

  Thysanocrinus 
  liliiformis 
  Hall 
  (Fig. 
  50) 
  (1852. 
  Pal. 
  N. 
  Y. 
  2:188, 
  

   pi. 
  42) 
  

  

  Distinguishing 
  characters. 
  Surface 
  of 
  plates 
  ornamented 
  by 
  verti- 
  

   cal 
  or 
  radiating, 
  interrupted 
  or 
  crenulated, 
  sharp, 
  elevated 
  striae; 
  

   small 
  infrabasals, 
  large 
  basals 
  and 
  still 
  larger 
  radials 
  ; 
  three 
  distichals 
  

   in 
  each 
  of 
  the 
  10 
  arms, 
  the 
  lowest 
  large 
  and 
  hexagonal, 
  the 
  others 
  

   cuneiform, 
  followed 
  by 
  the 
  biserial 
  upper 
  arm 
  plates; 
  stem 
  joints 
  

   _ 
  _ 
  round 
  and 
  alternatingly 
  thin 
  and 
  

  

  r- 
  

  

  tiiick, 
  most 
  irregular 
  near 
  the 
  

   base 
  of 
  the 
  calyx. 
  

  

  Found 
  so 
  far 
  only 
  in 
  the 
  

   Rochester 
  shale 
  at 
  Lockport 
  

   (Hall), 
  but 
  may 
  also 
  occur 
  at 
  

   Niagara. 
  

  

  Genus 
  lyric 
  crinus 
  Hall 
  

   [Ety 
  : 
  Xuptuu, 
  small 
  lyre; 
  xpcvov, 
  lily] 
  

   (1852. 
  Pal. 
  N. 
  Y. 
  2 
  :i97) 
  

   Calyx 
  depressed, 
  with 
  a 
  dicy- 
  

   clic 
  base. 
  Infrabasals 
  five; 
  ba- 
  

   sals 
  five, 
  pentagonal, 
  truncated 
  

   at 
  the 
  upper 
  end. 
  Radials 
  sepa- 
  

   rated 
  all 
  around 
  by 
  large 
  inter- 
  

   radials, 
  which 
  scarcely 
  dififer 
  

   from 
  the 
  anal 
  interradius. 
  Anal 
  

   aperture 
  eccentric. 
  Plates 
  of 
  the 
  

   calyx 
  smooth 
  or 
  finely 
  granu-' 
  

   lose. 
  Tegmen 
  almost 
  flat, 
  com- 
  

   posed 
  of 
  a 
  large 
  number 
  of 
  small 
  

   plates. 
  Arms 
  10, 
  strong, 
  simple 
  and 
  biserial. 
  Stem 
  round. 
  

  

  Lyriocrinus 
  dactylus 
  Hall 
  (Fig. 
  51) 
  (1852. 
  Pal. 
  N. 
  Y. 
  2:197, 
  

   pi. 
  44) 
  

  

  Distinguishing 
  characters. 
  Stem 
  near 
  the 
  calyx 
  of 
  alternating 
  

   larger 
  and 
  smaller 
  joints, 
  the 
  larger 
  projecting 
  much 
  beyond 
  the 
  

  

  Fig. 
  51 
  Lyriocrinus 
  dactylus 
  

  

  