﻿306 
  

  

  P. 
  H. 
  CAEEENTEE 
  ON 
  THE 
  EELATIONS 
  OE 
  

  

  plate." 
  An 
  intermediate 
  stage 
  between 
  the 
  two 
  is 
  afforded 
  by 
  Homo- 
  

   crinus 
  (fig. 
  III. 
  b), 
  which 
  differs 
  from 
  Dendrocrinus 
  " 
  only 
  in 
  having 
  

   the 
  suture 
  between 
  the 
  sections 
  of 
  the 
  compound 
  plate 
  sloping 
  

   instead 
  of 
  horizontal. 
  By 
  this, 
  in 
  itself, 
  trifling 
  alteration, 
  which 
  

   required 
  no 
  modification 
  in 
  the 
  form 
  or 
  construction 
  of 
  other 
  plates, 
  

   the 
  lower 
  portion 
  of 
  the 
  original 
  compound 
  radial 
  became 
  trans- 
  

   formed 
  into 
  an 
  anal 
  plate." 
  It 
  is 
  in 
  fact 
  " 
  pushed 
  slightly 
  to 
  the 
  

   rear, 
  thereby 
  becoming 
  a 
  regular 
  anal 
  plate 
  or 
  support 
  for 
  the 
  

   ventral 
  sac"*. 
  

  

  "While 
  entirely 
  concurring 
  in 
  the 
  views 
  of 
  Messrs. 
  Wachsmuth 
  

   and 
  Springer 
  respecting 
  the 
  mutual 
  relations 
  of 
  Hybocrinus, 
  Homo- 
  

   crinus, 
  and 
  Dendrocrinus, 
  I 
  am 
  not 
  altogether 
  in 
  accordance 
  with 
  

   them 
  as 
  to 
  the 
  relations 
  of 
  these 
  three 
  types 
  to 
  Iocrinus. 
  They 
  

   have 
  given 
  us 
  an 
  interpretation 
  f 
  of 
  the 
  calyx 
  of 
  this 
  type, 
  which 
  

   differs 
  considerably 
  from 
  that 
  given 
  by 
  Hall 
  and 
  by 
  Meek 
  and 
  

   Worthen. 
  I 
  can 
  offer 
  no 
  opinion 
  upon 
  this 
  point 
  ; 
  but, 
  assuming 
  

   that 
  their 
  analysis 
  of 
  the 
  Iocrinus- 
  calyx 
  is 
  the 
  right 
  one 
  (fig. 
  III. 
  c), 
  

   I 
  cannot 
  follow 
  their 
  comparison 
  of 
  it 
  with 
  Dendrocrinus. 
  The 
  

   bifurcating 
  plate, 
  which 
  gives 
  rise 
  both 
  to 
  the 
  right 
  posterior 
  ray 
  

   and 
  to 
  the 
  ventral 
  tube, 
  is 
  regarded 
  by 
  them 
  as 
  a 
  brachial 
  with 
  

   interradial 
  functions 
  ; 
  and 
  they 
  refer 
  to 
  Dendrocrinus 
  as 
  illustrating 
  

   this 
  point. 
  As 
  the 
  plate 
  in 
  question 
  is 
  supported 
  on 
  the 
  right 
  

   posterior 
  radial, 
  and 
  is 
  "of 
  the 
  same 
  width 
  as 
  the 
  other 
  brachials, 
  

   and 
  apparently 
  similarly 
  articulated," 
  it 
  is 
  probably 
  to 
  be 
  con- 
  

   sidered 
  a 
  modified 
  brachial. 
  But 
  the 
  lower 
  half 
  of 
  the 
  compound 
  

   radial 
  of 
  Dendrocrinus 
  (fig. 
  III. 
  a), 
  to 
  which 
  it 
  is 
  compared 
  by 
  

  

  Fig. 
  III. 
  — 
  Diagrams 
  illustrating 
  the 
  Anal 
  /System 
  of 
  the 
  Cyatho- 
  

   crinida?. 
  Copied 
  from 
  Wachsmuth 
  and 
  Springer. 
  

  

  

  y 
  &h 
  

  

  %uu 
  

  

  r, 
  Eadial. 
  b. 
  Basal. 
  

  

  A. 
  Dendrocrinus. 
  

  

  C. 
  Iocrinus 
  (fide 
  W. 
  & 
  S.). 
  

  

  Wo9Po 
  

  

  B 
  

   n. 
  Underbasal. 
  a. 
  Anal 
  system. 
  

  

  B. 
  Tiomocrinus 
  (emend., 
  W. 
  & 
  S.). 
  

  

  "Wachsmuth 
  and 
  Springer, 
  rests 
  on 
  two 
  basal 
  plates, 
  and 
  supports 
  

  

  the 
  right 
  posterior 
  radial, 
  which 
  itself 
  bears 
  the 
  brachials. 
  There 
  

  

  * 
  Revision, 
  pp. 
  66, 
  78. 
  t 
  Ibid. 
  p. 
  65. 
  

  

  