﻿The 
  Fatoa 
  of 
  the 
  Niagara 
  Group. 
  127 
  

  

  CRINOIDEA. 
  

  

  SACCOCRINUS 
  Hall. 
  

   Saccocrinus 
  Christyi 
  Hall. 
  

  

  Plate 
  13, 
  Figs. 
  13-20. 
  

  

  Actinocrinus 
  Christyi 
  Hall. 
  Trans. 
  Alb. 
  Inst., 
  vol. 
  iv, 
  p. 
  196. 
  Abstract, 
  p. 
  2; 
  

  

  May, 
  1863. 
  

   Not 
  Actinocrinus 
  Christyi 
  Shumard. 
  1st 
  and 
  2d 
  Rep. 
  Geol. 
  Surv. 
  Miss., 
  pt. 
  ii, 
  p. 
  

  

  191, 
  pi. 
  A, 
  fig. 
  3. 
  1855. 
  

   Actinocrinus 
  Whitfieldi 
  Hall. 
  20th 
  Rep. 
  N 
  Y. 
  St. 
  Cab. 
  Nat. 
  Hist., 
  p. 
  326; 
  Doc. 
  

  

  .Edit., 
  1868. 
  

   Actinocrinus 
  (Saccocrimis) 
  Whitfieldi 
  Hall.. 
  20th 
  Rep. 
  N. 
  Y. 
  St. 
  Cab. 
  Nat. 
  Hist., 
  

  

  pp. 
  370, 
  430 
  ; 
  Revised 
  Edit. 
  [1870.] 
  

   Saccocrums 
  Christyi 
  (Hall,) 
  M. 
  & 
  W. 
  Geol. 
  Rep. 
  111., 
  vol. 
  iii, 
  p. 
  317, 
  pi. 
  5, 
  fig. 
  1. 
  

  

  1868. 
  

   Megistocrinus 
  Marcouanus 
  W. 
  &M. 
  Mem. 
  Bost. 
  Soc. 
  Nat. 
  Hist., 
  vol. 
  i, 
  p. 
  87, 
  

  

  pi. 
  2, 
  fig. 
  5. 
  1866. 
  

   Megistocrinus 
  infelix 
  W. 
  & 
  M. 
  Mem. 
  Bost. 
  Soc. 
  Nat. 
  Hist., 
  vol. 
  i, 
  p. 
  110, 
  pi. 
  11, 
  

  

  Hg. 
  7. 
  1866. 
  

  

  Body 
  below 
  the 
  arms 
  elongate, 
  urn-shaped, 
  or 
  subovate, 
  very 
  

   slightly 
  spreading 
  at 
  the 
  arm-bases. 
  Basal 
  plates 
  proportion- 
  

   ally 
  small, 
  more 
  abruptly 
  spreading 
  than 
  the 
  succeeding 
  

   plates, 
  their 
  lower 
  margins 
  somewhat 
  produced 
  near 
  their 
  

   junction 
  with 
  the 
  column. 
  First 
  radial 
  plates 
  of 
  moderate 
  

   size, 
  height 
  and 
  width 
  equal, 
  those 
  of 
  the 
  postero-lateral 
  rays 
  

   smaller 
  ; 
  second 
  radial 
  plates 
  hexagonal, 
  somewhat 
  wider 
  than 
  

   high 
  ; 
  third 
  radials 
  heptagonal, 
  higher 
  than 
  wide, 
  smaller 
  

   than 
  the 
  second, 
  supporting 
  a 
  pair 
  of 
  supraradials 
  on 
  each 
  

   upper 
  sloping 
  side, 
  one 
  above 
  the 
  other, 
  the 
  upper 
  one 
  a 
  bifur- 
  

   cating 
  plate, 
  and 
  supporting 
  a 
  series 
  of 
  brachial 
  plates 
  on 
  

   each 
  upper 
  side, 
  giving 
  four 
  arms 
  to 
  each 
  ray. 
  Interradial 
  

   plates 
  numerous, 
  the 
  first 
  one 
  hexagonal, 
  intermediate 
  in 
  size 
  

   between 
  the 
  first 
  and 
  second 
  radials, 
  supporting 
  two 
  in 
  the 
  

   second 
  and 
  third 
  ranges 
  ; 
  about 
  five 
  other 
  ranges 
  above, 
  of 
  

   two 
  or 
  three 
  plates 
  each, 
  gradually 
  decreasing 
  in 
  size 
  toward 
  

   the 
  summit. 
  First 
  anal 
  plate 
  heptagonal, 
  equal 
  in 
  size 
  to 
  the 
  

   largest 
  first 
  radial, 
  but 
  shorter, 
  and 
  supporting 
  three 
  smaller 
  

  

  