﻿70 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  67 
  

  

  Arms 
  rounded 
  and 
  not 
  abutting. 
  

   IBr 
  not 
  more 
  than 
  2. 
  

  

  Column 
  round 
  Pachylocrinus. 
  

  

  (Olim 
  Scaphiocrinus). 
  

  

  Column 
  pentagonal 
  Abrotocrinus. 
  

  

  IBr 
  more 
  than 
  2. 
  Arms 
  branching 
  unequally 
  

  

  beyond 
  them 
  Culmicrinus. 
  

  

  Sac 
  with 
  strong 
  median 
  row 
  of 
  plates 
  Liparocrinus. 
  

  

  Ileterotomous. 
  

  

  Brachials 
  cuneiform 
  or 
  biserial, 
  arms 
  not 
  abutting. 
  

   Sac 
  balloon-shaped, 
  exceptionally 
  spiniferous. 
  

  

  Cup 
  turbinate 
  Coeliocrinus. 
  

  

  Sac 
  mushroom-shaped, 
  spiniferous. 
  

  

  Cup 
  low, 
  cup-shaped 
  Hydreionocrinus. 
  

  

  Brachials 
  quadrangular, 
  uniserial. 
  

   Sac 
  club-shaped 
  or 
  pyramidal. 
  

  

  Arms 
  closely 
  abutting 
  Zeacrinus. 
  

  

  Arms 
  branching 
  once 
  on 
  IIBr. 
  

   Arms 
  not 
  abutting 
  ; 
  4 
  to 
  the 
  ray, 
  exceptionally 
  3 
  or 
  2. 
  

  

  Dichotomous 
  : 
  brachials 
  cuneiform, 
  fairly 
  long 
  Ulrichicrinus. 
  

  

  brachials 
  quadrangular, 
  very 
  short, 
  

  

  arms 
  heavy 
  Woodocrinus. 
  

  

  Arms 
  not 
  branching 
  beyond 
  IIBr. 
  

   10 
  main 
  rami, 
  unbranched. 
  

   Brachials 
  cuneiform. 
  

   Bearing 
  strong 
  ramules. 
  

   Cup 
  usually 
  depressed, 
  with 
  flat 
  or 
  concave 
  base. 
  

  

  Anal 
  opening 
  directly 
  through 
  side 
  of 
  sac 
  Decadocrinus. 
  

  

  Anal 
  opening 
  at 
  end 
  of 
  lateral 
  spout 
  Aulocrinus. 
  

  

  Bearing 
  ordinary 
  pinnules. 
  

   Cup 
  usually 
  elongate, 
  sometimes 
  obconical 
  to 
  

   low 
  bowl-shaped, 
  rounded 
  base. 
  

   Anal 
  opening 
  directly 
  through 
  sac 
  Scytalocrinus. 
  

  

  Genus 
  PACHYLOCRINUS 
  Wachsmuth 
  and 
  Springer 
  

   Plate 
  16 
  

  

  Scaphiocrinus 
  Hall, 
  Geol. 
  Iowa, 
  pt. 
  2, 
  185S, 
  p. 
  550. 
  — 
  Wachsmuth 
  and 
  

   Speingeb, 
  Rev. 
  Pal., 
  pt. 
  1, 
  1S79, 
  p. 
  112 
  ; 
  pt. 
  3, 
  1886, 
  p. 
  235. 
  

  

  Pachylocrinus 
  Wachsmuth 
  and 
  Springer, 
  Rev. 
  Pal., 
  pt. 
  1, 
  1879, 
  p. 
  115 
  ; 
  

   pt. 
  3, 
  p. 
  242. 
  — 
  Springer, 
  New 
  Amer. 
  Foss. 
  Crin., 
  1911, 
  p. 
  145. 
  — 
  Zittel- 
  

   Eastman, 
  Textb. 
  Pal., 
  1913, 
  p. 
  222. 
  

  

  Mississippian 
  ; 
  Kinderhook 
  to 
  Upper 
  Carboniferous. 
  

  

  The 
  reason 
  for 
  adopting 
  this 
  name 
  for 
  a 
  majority 
  of 
  the 
  great 
  

   number 
  of 
  species 
  described 
  under 
  Scaphiocrinus 
  (nomen 
  nudum 
  

   because 
  its 
  type 
  species 
  belonged 
  to 
  the 
  previously 
  established 
  

   Graphiocrinus) 
  were 
  set 
  forth 
  in 
  my 
  paper 
  of 
  1911, 
  above 
  cited. 
  It 
  

   is 
  one 
  of 
  the 
  most 
  prolific 
  and 
  long 
  lived 
  of 
  Carboniferous 
  types, 
  

   containing, 
  before 
  removal 
  of 
  those 
  with 
  pentagonal 
  stem 
  under 
  

   Abrotocrinus, 
  upwards" 
  of 
  100 
  described 
  species, 
  ranging 
  from 
  the 
  

   Kinderhook 
  to 
  the 
  Upper 
  Carboniferous. 
  Although 
  having 
  typi- 
  

  

  