﻿The 
  Fauna 
  of 
  the 
  Niagara 
  Group. 
  

  

  147 
  

  

  The 
  following 
  diagrams 
  illustrate 
  the 
  generic 
  structure 
  : 
  

   Fig. 
  1 
  has 
  the 
  general 
  form 
  and 
  proportions 
  of 
  plates 
  shown 
  

   in 
  C. 
  stigmatus 
  of 
  Plate 
  19. 
  Fig. 
  2 
  shows 
  a 
  different 
  propor- 
  

   tion 
  of 
  the 
  parts. 
  

  

  X 
  \/ 
  Op 
  

  

  e3 
  cxi 
  

  

  

  4> 
  

  

  Calceocrinus 
  tunicatus. 
  

  

  ^y^fc 
  

  

  IB 
  

  

  Calceocrinus 
  chrysalis. 
  

  

  Fig. 
  1. 
  — 
  1 
  The 
  basal 
  plate 
  with 
  cicatrix 
  for 
  the 
  column 
  attachment 
  10 
  ; 
  2 
  the 
  

   dorso-basal 
  plate 
  ; 
  3 
  3 
  the 
  dorso-lateral 
  plates 
  ; 
  4 
  the 
  dorso-radial 
  plate 
  ; 
  a 
  the 
  face 
  

   of 
  attachment 
  for 
  the 
  dorsal 
  arms 
  ; 
  d 
  d 
  faces 
  of 
  attachment 
  for 
  the 
  lateral 
  arms 
  ; 
  

   c 
  the 
  faces 
  of 
  attachment 
  for 
  the 
  strong 
  ligament 
  between 
  the 
  basal 
  and 
  lower 
  

   dorsal 
  plates. 
  

  

  Fig. 
  2 
  has 
  the 
  same 
  general 
  structure, 
  except 
  that 
  the 
  dorsal 
  plate 
  2 
  is 
  narrow 
  

   and 
  elongate 
  : 
  3 
  4 
  and 
  10 
  have 
  the 
  same 
  significance 
  as 
  in 
  Fig. 
  1 
  ; 
  5 
  5 
  5 
  5 
  are 
  plates 
  

   of 
  the 
  dorsal 
  arm 
  ; 
  6 
  6 
  lateral 
  brachial 
  plates 
  ; 
  7 
  7 
  the 
  lateral 
  arms 
  and 
  their 
  

   subdivisions. 
  

  

  Calceocrinus 
  stigmatus. 
  

  

  Plate 
  19, 
  Figs. 
  9-11. 
  

  

  Cheirocrinus 
  stigmatus 
  Hall. 
  Trans. 
  Alb. 
  Inst., 
  vol. 
  iv, 
  p. 
  225. 
  Abstract, 
  p. 
  31; 
  

   1862. 
  

  

  In 
  the 
  collection 
  at 
  present 
  before 
  me, 
  this 
  species 
  is 
  illus- 
  

   trated 
  by 
  the 
  basal 
  portions 
  of 
  the 
  body, 
  some 
  fragments 
  of 
  

   the 
  arms, 
  and 
  a 
  single 
  specimen 
  which 
  preserves 
  the 
  basal 
  

   plate 
  of 
  the 
  dorsal 
  arm. 
  The 
  dorso-lateral 
  plates 
  are 
  so 
  closely 
  

   anchylosed 
  that 
  no 
  line 
  of 
  separation 
  is 
  observable, 
  and 
  the 
  

   same 
  is 
  often 
  true 
  of 
  the 
  dorso-radial 
  plate 
  and 
  the 
  second 
  or 
  

   lower 
  dorsal 
  plate, 
  which 
  bears 
  upon 
  its 
  lower 
  margin 
  the 
  cica- 
  

   trices 
  for 
  the 
  muscular 
  attachment 
  of 
  the 
  basal 
  plate. 
  The 
  

   cicatrices 
  for 
  the 
  three 
  sets 
  of 
  arms 
  are 
  well 
  preserved. 
  

  

  The 
  species 
  differs 
  from 
  any 
  other 
  known 
  to 
  me 
  in 
  the 
  closely 
  

   anchylosed 
  condition 
  of 
  the 
  dorso-]ateral 
  plates, 
  which 
  also 
  

   involves 
  the 
  lower 
  dorsal 
  plate. 
  The 
  surface 
  is 
  marked 
  by 
  

   fine 
  granule© 
  or 
  undulating 
  and 
  tortuous 
  granulose 
  striae. 
  

  

  