﻿Plate 
  2 
  

  

  All 
  figures 
  not 
  otherwise 
  noted 
  natural 
  size 
  

  

  Page. 
  

   MYELODACTYLUS 
  AMMONIS 
  i 
  Bather) 
  10 
  

  

  Fig. 
  1. 
  A 
  rinse 
  coil, 
  with 
  stem 
  tapering 
  to 
  a 
  point; 
  cuneate 
  interlock- 
  

   ing 
  columnals 
  with 
  a 
  cirrus 
  from 
  the 
  broad 
  end 
  of 
  each 
  : 
  

   cirri 
  converging 
  to 
  center, 
  completely 
  enveloping 
  the 
  crown. 
  

   X 
  |. 
  

  

  la. 
  The 
  same 
  specimen, 
  seen 
  from 
  outer 
  curve, 
  showing 
  the 
  rapid 
  

   taper 
  of 
  stem 
  to 
  a 
  narrow 
  distal 
  end: 
  longitudinal 
  sutures 
  

   not 
  visible 
  in 
  this 
  specimen. 
  X 
  \. 
  

  

  lit. 
  Tin' 
  alternate 
  succession 
  of 
  columnals 
  in 
  outline 
  var. 
  alterni 
  

   cirrus. 
  

  

  2. 
  A 
  similar 
  specimen 
  (figure 
  not 
  enlarged), 
  with 
  hour-glass 
  shaped 
  

  

  columnals 
  bearing 
  a 
  cirrus 
  at 
  each 
  end. 
  and 
  lenticular, 
  non 
  

  

  eirriferous 
  ossicles 
  interposed. 
  

   2a. 
  The 
  same 
  seen 
  from 
  the 
  outer 
  curve, 
  tapering 
  to 
  a 
  point, 
  and 
  

  

  with 
  longitudinal 
  sutures 
  strongly 
  developed. 
  X 
  |. 
  

   2b. 
  The 
  paired 
  succession 
  of 
  cirri 
  in 
  outline 
  — 
  var. 
  bijugicirrus. 
  

  

  3. 
  A 
  small 
  specimen 
  of 
  similar 
  type 
  to 
  last, 
  with 
  strong 
  distal 
  

  

  taper. 
  X 
  4. 
  

   3«. 
  The 
  outer 
  side 
  of 
  same 
  specimen 
  as 
  it 
  would 
  appear 
  if 
  stretched 
  

  

  out 
  straight 
  : 
  to 
  show 
  the 
  great 
  relative 
  breadth 
  in 
  the 
  middle 
  

  

  region, 
  narrowing 
  both 
  ways, 
  and 
  ending 
  distally 
  in 
  a 
  point; 
  

  

  outer 
  longitudinal 
  sutures 
  strong. 
  X 
  f. 
  

   3b. 
  The 
  distal 
  end 
  of 
  same. 
  > 
  

   3c. 
  The 
  succession 
  of 
  columnals 
  in 
  outline, 
  with 
  paired 
  arrangement 
  

  

  of 
  cirri 
  — 
  var. 
  bljug'wirrus. 
  

  

  4. 
  A 
  similar 
  specimen, 
  with 
  alternate 
  cuneate 
  columnals: 
  small 
  part 
  

  

  of 
  proximal 
  coil 
  is 
  shown. 
  X 
  4. 
  

   4a, 
  b. 
  The 
  tapering 
  distal 
  end. 
  ami 
  the 
  succession 
  of 
  columnals 
  in 
  out- 
  

   line 
  var. 
  altermcirrus. 
  

   f>. 
  Part 
  of 
  a 
  remnant 
  of 
  two 
  coils, 
  from 
  the 
  inner 
  side 
  of 
  the 
  inner- 
  

   most 
  coil, 
  showing 
  the 
  form 
  and 
  arrangement 
  of 
  columnals 
  

   for 
  the 
  paired 
  cirri 
  — 
  var. 
  bijugicirrus. 
  X 
  f. 
  

   5a. 
  Transverse 
  view 
  of 
  the 
  fractured 
  secfon 
  of 
  the 
  two 
  coils, 
  the 
  

   upper 
  one 
  being 
  near 
  the 
  distal 
  end. 
  therefore 
  thicker 
  and 
  

   narrower 
  than 
  the 
  lower. 
  < 
  f. 
  

  

  All 
  the 
  foregoing 
  are 
  from 
  the 
  Brownsport 
  limestone, 
  

   Niagaran 
  ; 
  Decatur 
  County. 
  Tennessee. 
  

   (>. 
  Specimen 
  with 
  three 
  involute 
  coils, 
  tapering 
  to 
  a 
  narrow 
  distal 
  

   end. 
  The 
  cirri 
  have 
  mostly 
  fallen 
  away, 
  exposing 
  the 
  proxi- 
  

   mal 
  evolute 
  coil 
  with 
  the 
  slender, 
  circular 
  neck 
  leading 
  to 
  the 
  

   faintly 
  outlined 
  crown 
  lying 
  along 
  the 
  concave 
  side 
  of 
  the 
  

   middle 
  coil. 
  

   G«. 
  Outer 
  curve 
  of 
  same, 
  showing 
  distal 
  end 
  and 
  longitudinal 
  

   sutures. 
  

  

  9!) 
  

  

  