﻿86 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  G7 
  

  

  was 
  doubtless 
  at 
  the 
  side 
  of 
  the 
  neck, 
  near 
  the 
  base 
  of 
  the 
  arms. 
  This 
  aperture, 
  

   however, 
  has 
  not 
  been 
  observed, 
  although 
  a 
  separated 
  sack 
  of 
  C. 
  dilatatus 
  has 
  

   been 
  carefully 
  examined, 
  together 
  with 
  more 
  than 
  half 
  its 
  neck, 
  without 
  the 
  

   discovery 
  of 
  any 
  aperture 
  whatever, 
  and 
  four 
  plates 
  of 
  the 
  anal 
  series 
  seen, 
  

   with 
  no 
  better 
  result. 
  

  

  The 
  genus 
  was 
  founded 
  upon 
  three 
  species, 
  Poteriocrinus 
  dilatatus 
  

   and 
  P. 
  ventricosus, 
  previously 
  described 
  by 
  Hall, 
  and 
  Goeliocrinus 
  

   subspinosus 
  of 
  White, 
  then 
  described, 
  all 
  from 
  the 
  Burlington 
  lime- 
  

   stone. 
  P. 
  dilatatus 
  was 
  designated 
  as 
  the 
  genotype. 
  The 
  descriptions 
  

   of 
  these 
  species 
  were 
  unaccompanied 
  by 
  any 
  figures, 
  and 
  none 
  of 
  them 
  

   has 
  since 
  been 
  illustrated, 
  save 
  by 
  an 
  incidental 
  figure 
  of 
  the 
  inflated 
  

   sac 
  of 
  C 
  . 
  ventricosus 
  given 
  by 
  Wachsmuth 
  and 
  Springer 
  on 
  plate 
  7 
  

   of 
  the 
  Camerata 
  Monograph, 
  and 
  one 
  of 
  C. 
  dilatatus 
  by 
  Whitfield 
  

   (not 
  of 
  the 
  type) 
  in 
  1893. 
  The 
  arm 
  branching 
  is 
  of 
  the 
  hetero- 
  

   tomous 
  type 
  in 
  principle, 
  but 
  not 
  very 
  well 
  defined, 
  there 
  being 
  

   usually 
  seen 
  only 
  a 
  single 
  bifurcation 
  beyond 
  the 
  IIBr, 
  on 
  the 
  outer 
  

   arm 
  of 
  the 
  ray, 
  the 
  inner 
  arm 
  of 
  equal 
  size 
  usually 
  remaining 
  un- 
  

   branched. 
  It 
  is 
  a 
  sort 
  of 
  intermediate 
  stage 
  between 
  dichotomy 
  and 
  

   heterotomy, 
  which 
  might 
  fall 
  under 
  either 
  term 
  in 
  some 
  cases. 
  

  

  GOELIOCRINUS 
  DILATATUS 
  (Hall) 
  

  

  Plate 
  24, 
  figs. 
  9-13 
  

  

  Poteriocrinus 
  dilatatus 
  Hall, 
  Journ. 
  Boston 
  Soc. 
  Nat. 
  Hist., 
  vol. 
  7, 
  1861, 
  

   p. 
  300. 
  

  

  Coeliocrinus 
  dilatatus, 
  White, 
  Boston 
  Journ. 
  Nat. 
  Hist., 
  vol. 
  7, 
  1S63, 
  p. 
  

   501. 
  — 
  Wachsmuth 
  and 
  Springer, 
  Rev. 
  Pal., 
  pt. 
  1, 
  1879,, 
  p. 
  133. 
  — 
  Whit- 
  

   field, 
  Mem. 
  Amer. 
  Mus. 
  Nat. 
  Hist., 
  vol. 
  1, 
  1893, 
  pi. 
  3, 
  fig. 
  18. 
  

  

  Lower 
  Burlington 
  limestone 
  ; 
  Burlington, 
  Iowa. 
  

  

  COELIOCRINUS 
  VENTRICOSUS 
  (Hall) 
  

  

  Plate 
  24, 
  figs. 
  1-8 
  ; 
  plate 
  25, 
  fig. 
  1 
  

  

  Poteriocrinus 
  ventricosus 
  Hall, 
  Journ. 
  Boston 
  Soc. 
  Nat. 
  Hist., 
  vol. 
  7, 
  1861, 
  

  

  p. 
  301. 
  

   Coeliocrinus 
  ventricosus, 
  White, 
  Boston 
  Journ. 
  Nat. 
  Hist., 
  vol. 
  7, 
  1863, 
  p. 
  

   501. 
  — 
  Wachsmuth 
  and 
  Springer, 
  Rev. 
  Pal., 
  pt. 
  1, 
  1879, 
  p. 
  133 
  ; 
  North 
  

  

  Amer. 
  Crin. 
  Cam., 
  1897, 
  pi. 
  7, 
  figs. 
  10a, 
  b. 
  

   Lower 
  Burlington 
  limestone 
  ; 
  Burlington, 
  Iowa. 
  

  

  COELIOCRINUS 
  SUBSPINOSUS 
  White 
  

  

  Plate 
  25, 
  figs. 
  2, 
  3 
  

  

  Coeliocrinus 
  subspinosus 
  White, 
  Boston 
  Journ. 
  Nat. 
  Hist., 
  vol. 
  7, 
  1863, 
  p. 
  

  

  501. 
  — 
  Wachsmuth 
  and 
  Springer, 
  Rev. 
  Pal., 
  pi. 
  1, 
  1879, 
  p. 
  133. 
  

   Upper 
  Burlington 
  limestone 
  ; 
  Burlington, 
  Iowa. 
  

  

  The 
  three 
  foregoing 
  species 
  agree 
  in 
  having 
  a 
  cup-shaped, 
  ex- 
  

   panding 
  calyx, 
  with 
  a 
  narrow 
  conical 
  base, 
  as 
  distinguished 
  from 
  

  

  