﻿14 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.67 
  

  

  lowing 
  species 
  exists 
  also 
  in 
  the 
  Laurel 
  formation; 
  it 
  has 
  the 
  cirri 
  

   paired 
  on 
  alternate 
  columnals, 
  the 
  cirriferous 
  ossicles 
  having 
  an 
  

   hour-glass 
  shape 
  as 
  seen 
  from 
  the 
  inner 
  side 
  of 
  the 
  curve, 
  with 
  a 
  

   shorter, 
  lenticular 
  one 
  between 
  them 
  (pi. 
  2, 
  fig. 
  5). 
  Also 
  Wenlockian 
  

   Gotland, 
  Sweden, 
  and 
  probably 
  Dudley, 
  England. 
  

  

  MYELODACTYLUS 
  EXTENSUS, 
  new 
  species 
  

  

  Plate 
  3, 
  figs. 
  1-lSa 
  

  

  Like 
  M. 
  ammonis, 
  except 
  that 
  the 
  coil 
  is 
  open 
  beyond 
  the 
  proximal 
  

   region; 
  stem 
  elongate 
  and 
  extended 
  for 
  a 
  considerable 
  distance 
  in 
  a 
  

   broad 
  curve 
  toward 
  the 
  distal 
  end. 
  

  

  This 
  species, 
  differing 
  from 
  the 
  preceding 
  only 
  in 
  the 
  extent 
  and 
  

   mode 
  of 
  termination 
  of 
  the 
  stem, 
  is 
  represented 
  by 
  a 
  series 
  of 
  about 
  

   30 
  specimens, 
  which 
  for 
  the 
  most 
  part 
  are 
  considerably 
  the 
  largest 
  

   of 
  the 
  two. 
  In 
  diameter 
  of 
  the 
  corresponding 
  coil 
  they 
  range 
  from 
  

   12 
  mm. 
  to 
  30 
  mm., 
  to 
  which 
  must 
  be 
  added 
  the 
  extension 
  of 
  the 
  stem 
  

   after 
  deviating 
  from 
  the 
  coil. 
  In 
  one 
  specimen 
  with 
  the 
  close 
  coil 
  

   about 
  25 
  mm. 
  in 
  diameter 
  the 
  total 
  length 
  of 
  the 
  bilateral 
  part 
  of 
  the 
  

   stem 
  is 
  about 
  16 
  cm., 
  of 
  which 
  more 
  than 
  half 
  lies 
  beyond 
  the 
  region 
  

   of 
  the 
  coil, 
  without 
  reaching 
  the 
  distal 
  end, 
  and 
  with 
  but 
  little 
  

   diminution; 
  and 
  it 
  is 
  almost 
  straight 
  (pi. 
  3, 
  fig. 
  1). 
  In 
  another, 
  in 
  

   which 
  the 
  coil 
  is 
  loosely 
  maintained 
  in 
  large 
  curves, 
  the 
  stem 
  is 
  

   preserved 
  to 
  near 
  the 
  distal 
  end, 
  where 
  it 
  seems 
  to 
  terminate 
  in 
  some 
  

   small 
  radicular 
  cirri 
  (pi. 
  3, 
  fig. 
  3). 
  Another 
  specimen 
  has 
  a 
  close 
  

   coil 
  of 
  12 
  mm., 
  from 
  which 
  it 
  opens 
  in 
  a 
  broad 
  coil 
  for 
  one 
  and 
  a 
  

   half 
  whorls 
  more 
  for 
  about 
  12 
  cm., 
  maintaining 
  a 
  width 
  of 
  about 
  

   3.5 
  mm. 
  to 
  near 
  the 
  distal 
  end, 
  where 
  it 
  diminishes 
  to 
  2.5 
  mm. 
  (pi. 
  3, 
  

   fig. 
  5). 
  Another, 
  not 
  figured, 
  has 
  the 
  stem 
  extended 
  beyond 
  the 
  

   point 
  of 
  deviation 
  for 
  a 
  distance 
  of 
  12 
  cm. 
  and 
  is 
  still 
  large, 
  having 
  

   diminished 
  in 
  width 
  from 
  5 
  mm. 
  in 
  the 
  median 
  part 
  to 
  4 
  mm. 
  Besides 
  

   the 
  other 
  specimens 
  with 
  long 
  extension 
  shown 
  on 
  the 
  plate, 
  there 
  

   are 
  three 
  more 
  with 
  incomplete 
  extended 
  part 
  from 
  4 
  to 
  6 
  cm. 
  long, 
  

   with 
  little 
  or 
  no 
  diminution, 
  thus 
  giving 
  ten 
  specimens 
  in 
  which 
  this 
  

   character 
  is 
  strongly 
  emphasized, 
  in 
  contrast 
  to 
  the 
  still 
  greater 
  

   number 
  belonging 
  to 
  31. 
  anwwnis 
  in 
  which 
  the 
  stem 
  is 
  restricted 
  to 
  

   the 
  close 
  coil 
  with 
  its 
  pointed 
  distal 
  end. 
  The 
  small 
  size 
  in 
  which 
  

   this 
  form 
  also 
  occurs 
  is 
  shown 
  by 
  figures 
  10 
  and 
  11 
  of 
  plate 
  3. 
  

  

  The 
  open 
  coiled 
  form 
  would 
  seem 
  to 
  be 
  favorable 
  for 
  the 
  discovery 
  

   of 
  the 
  crown; 
  and 
  in 
  view 
  of 
  the 
  fine 
  preservation 
  of 
  many 
  of 
  the 
  

   specimens 
  from 
  the 
  Decatur 
  county 
  locality 
  I 
  fully 
  expected 
  to 
  find 
  

   it. 
  But 
  after 
  diligent 
  search 
  I 
  was 
  only 
  able 
  to 
  uncover 
  it, 
  in 
  

   imperfect 
  condition, 
  in 
  a 
  few 
  specimens, 
  not 
  well 
  enough 
  preserved 
  

   to 
  show 
  the 
  composition 
  of 
  the 
  calyx. 
  I 
  then 
  tried 
  grinding, 
  and 
  

  

  