﻿20 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL, 
  MUSEUM 
  vol. 
  07 
  

  

  MYELODACTYLUS 
  NODOSARIUS 
  (Hall) 
  

  

  Plate 
  5, 
  figs. 
  1-8. 
  

  

  Brachiocrinus 
  nodosarius 
  Hall, 
  Pal. 
  New 
  York, 
  vol. 
  3, 
  1859, 
  p. 
  IIS, 
  pi. 
  5, 
  

  

  figs. 
  5, 
  6, 
  7 
  ; 
  pi. 
  6, 
  figs. 
  1, 
  2, 
  3. 
  

   Herpctocrinus 
  nodosarius, 
  Bather, 
  Amer. 
  Geol., 
  vol. 
  16, 
  1895, 
  pp. 
  213, 
  217. 
  — 
  

  

  Brachiocrinus 
  (Herpetocrinus) 
  nodosarius, 
  Talhot, 
  Amer. 
  Journ. 
  Sri., 
  

  

  20, 
  1905, 
  p. 
  32. 
  — 
  Brachiocrinus 
  nodosarius, 
  Kirk, 
  Proc. 
  U. 
  S. 
  Nat. 
  Mus.. 
  

  

  vol. 
  41, 
  1911, 
  p. 
  48. 
  — 
  Brachiocrinus 
  nodosarius, 
  Goldring, 
  Devonian 
  

  

  Crinoids 
  of 
  New 
  York, 
  1924, 
  p. 
  332, 
  pi. 
  41, 
  figs. 
  1-4. 
  

  

  Coil 
  open. 
  Stem 
  elongate, 
  extending 
  without 
  sensible 
  diminu- 
  

   tion 
  considerably 
  beyond 
  the 
  coil, 
  terminating 
  in 
  a 
  bulbous 
  enlarge- 
  

   ment; 
  columnals 
  short, 
  uniform. 
  Cirri 
  few, 
  short 
  and 
  thick, 
  com- 
  

   posed 
  of 
  a 
  few 
  rounded 
  cirrals 
  ; 
  monilif 
  orm, 
  thickest 
  about 
  the 
  mid- 
  

   dle, 
  where 
  their 
  diameter 
  often 
  exceeds 
  that 
  of 
  the 
  stem 
  from 
  which 
  

   they 
  spring; 
  alternating, 
  at 
  intervals 
  of 
  usually 
  1 
  to 
  5 
  columnals. 
  

  

  The 
  most 
  remarkable 
  thing 
  about 
  this 
  Lower 
  Devonian 
  form 
  is 
  the 
  

   ponderous 
  character 
  of 
  its 
  rounded, 
  bead-like, 
  doubly 
  tapering 
  cirri. 
  

   In 
  this 
  respect 
  it 
  evolved 
  an 
  unparalleled 
  modification, 
  for 
  in 
  no 
  

   other 
  known 
  crinoid 
  are 
  the 
  cirri 
  thicker 
  than 
  the 
  stem 
  on 
  which 
  

   they 
  are 
  borne. 
  Here 
  they 
  are 
  often 
  very 
  much 
  thicker. 
  In 
  three 
  

   specimens 
  with 
  stems 
  3 
  mm. 
  wide 
  many 
  of 
  the 
  cirri 
  are 
  4 
  mm. 
  in 
  

   width; 
  and 
  in 
  all 
  the 
  ten 
  specimens 
  in 
  hand 
  the 
  cirri 
  are 
  nearly 
  all 
  

   as 
  thick 
  as, 
  or 
  thicker 
  than, 
  the 
  stem. 
  There 
  is 
  considerable 
  irregu- 
  

   larity 
  in 
  the 
  size 
  of 
  the 
  cirri, 
  and 
  one 
  gets 
  the 
  impression 
  of 
  hyper- 
  

   trophy 
  due 
  to 
  some 
  unusual 
  stimulus. 
  

  

  Some 
  are 
  decidedly 
  swollen 
  in 
  the 
  middle, 
  increasing 
  in 
  size 
  for 
  a 
  

   few 
  ossicles, 
  and 
  then 
  diminish 
  to 
  sharp 
  extremities. 
  Some 
  are 
  about 
  

   equal 
  throughout, 
  and 
  often 
  both 
  kinds 
  are 
  seen 
  in 
  the 
  same 
  speci- 
  

   men 
  ; 
  usually 
  the 
  first 
  cirral 
  is 
  shorter 
  than 
  those 
  directly 
  following 
  

   it. 
  The 
  cirri 
  originate 
  along 
  the 
  curved 
  outer 
  margins 
  of 
  the 
  modi- 
  

   fied 
  stem, 
  alternately 
  at 
  the 
  longer 
  face 
  of 
  successive 
  cuneate 
  col- 
  

   umnals, 
  giving 
  them 
  often 
  the 
  appearance 
  of 
  being 
  opposite, 
  and 
  in 
  

   pairs. 
  Beginning 
  at 
  the 
  distal 
  end 
  of 
  the 
  stem, 
  the 
  first 
  few 
  cirri 
  

   are 
  in 
  close 
  contact, 
  but 
  higher 
  up 
  they 
  are 
  separated 
  by 
  increasing 
  

   intervals 
  of 
  one 
  to 
  five 
  columnals, 
  which 
  are 
  short 
  and 
  equal. 
  Oc- 
  

   casionally 
  the 
  two 
  cirrus-bearing 
  columnals 
  are 
  fused. 
  

  

  The 
  cirri 
  are 
  few 
  in 
  number, 
  not 
  exceeding 
  eight 
  to 
  ten 
  pairs 
  in 
  

   the 
  longest 
  stems 
  observed, 
  which 
  are 
  5 
  to 
  10 
  cm. 
  in 
  length, 
  without 
  

   being 
  complete. 
  One 
  of 
  these 
  is 
  almost 
  straight 
  for 
  its 
  entire 
  

   length. 
  The 
  proximal 
  part 
  of 
  the 
  stem, 
  and 
  also 
  the 
  crown, 
  are 
  un- 
  

   known. 
  

  

  Another 
  character 
  wherein 
  this 
  form 
  is 
  unique 
  among 
  its 
  con- 
  

   geners 
  is 
  that 
  the 
  distal 
  end 
  of 
  the 
  stem 
  terminates 
  in 
  a 
  rounded 
  con- 
  

   dyle 
  having 
  the 
  appearance 
  of 
  a 
  secondary 
  growth 
  after 
  fracture 
  of 
  

  

  