﻿aut9 
  UNUSUAL 
  FORMS 
  OF 
  FOSSIL 
  CRINOIDS 
  SPRINGER 
  47 
  

  

  Genus 
  PTEROTOCR1NUS 
  Lyon 
  and 
  Casseday 
  

  

  Plates 
  13, 
  14 
  

  

  Asterocrinus 
  Lyon, 
  Geol. 
  Rep. 
  Kentucky, 
  vol. 
  3, 
  1857, 
  p. 
  472.— 
  Ptero- 
  

   tocrinus 
  Lyon 
  and 
  Casseday, 
  Amer. 
  Journ. 
  Sci. 
  and 
  Arts, 
  vol. 
  29, 
  

   1S60, 
  p. 
  68.— 
  Wachsmuth 
  and 
  Springer, 
  Rev. 
  Pal., 
  pt 
  2, 
  1881, 
  p. 
  87; 
  

   North 
  Ainer. 
  Crin. 
  Cam., 
  1897, 
  p. 
  791. 
  

  

  Mississippian, 
  Upper 
  Chester. 
  

  

  This 
  genus 
  was 
  proposed 
  by 
  Lyon 
  under 
  the 
  name 
  Asterocrinus 
  

   with 
  two 
  species, 
  A. 
  capitalis 
  and 
  A. 
  corona 
  r'ms, 
  which 
  being 
  pre- 
  

   occupied 
  was 
  afterwards 
  changed 
  by 
  Lyon 
  and 
  Casseday 
  to 
  Pteroto- 
  

   erinus, 
  and 
  three 
  new 
  species 
  described. 
  The 
  several 
  species 
  are 
  

   illustrated 
  by 
  Wachsmuth 
  and 
  Springer 
  ; 
  25 
  but 
  I 
  am 
  adding 
  some 
  

   new 
  figures, 
  1, 
  to 
  illustrate 
  a 
  species 
  of 
  Lyon 
  and 
  Casseday 
  that 
  was 
  

   never 
  figured 
  ; 
  2, 
  to 
  clarify 
  the 
  account 
  of 
  the 
  most 
  remarkable 
  of 
  all 
  

   the 
  species, 
  not 
  hitherto 
  understood 
  for 
  lack 
  of 
  proper 
  illustration; 
  

   and 
  3, 
  to 
  give 
  along 
  with 
  them 
  a 
  good 
  representation 
  of 
  the 
  other 
  

   leading 
  species. 
  

  

  PTEROTOCRINUS 
  RUGOSUS 
  Lyon 
  and 
  Casseday 
  

  

  Plate 
  13, 
  figs. 
  17-20 
  

  

  Pterotocrinus 
  rugosus 
  Lyon 
  and 
  Casseday, 
  Amer. 
  Journ. 
  Sci. 
  and 
  Arts, 
  

   vol. 
  29, 
  1860, 
  p. 
  71. 
  

  

  The 
  description, 
  unaccompanied 
  by 
  any 
  figure, 
  is 
  as 
  follows: 
  

  

  The 
  condition 
  of 
  our 
  specimen 
  is 
  such 
  that 
  a 
  particular 
  description 
  can 
  not 
  

   be 
  made 
  ; 
  the 
  arrangement 
  of 
  the 
  parts, 
  however, 
  is 
  evidently 
  quite 
  similar 
  

   to 
  that 
  of 
  P. 
  depressus. 
  The 
  basals, 
  first, 
  second, 
  and 
  third 
  radials 
  are 
  present, 
  

   together 
  with 
  parts 
  of 
  the 
  wings 
  and 
  a 
  portion 
  of 
  one 
  of 
  the 
  arms. 
  This 
  

   species 
  differs 
  remarkably 
  from 
  P. 
  depressus 
  in 
  the 
  greater 
  thickness 
  of 
  the 
  

   pieces, 
  prominence 
  of 
  the 
  base, 
  the 
  knobby 
  protuberances 
  upon 
  it 
  and 
  upon 
  

   the 
  first 
  radials, 
  the 
  depth 
  of 
  the 
  columnar 
  pit, 
  as 
  well 
  as 
  by 
  its 
  roughness 
  and 
  

   more 
  robust 
  appearance. 
  

  

  This 
  species 
  was 
  founded 
  upon 
  a 
  " 
  single 
  crushed 
  and 
  imperfect 
  

   specimen," 
  which 
  I 
  am 
  now 
  figuring 
  after 
  being 
  developed 
  by 
  further 
  

   preparation, 
  together 
  with 
  three 
  other 
  calices 
  which 
  confirm 
  the 
  de- 
  

   scription 
  very 
  clearly. 
  This 
  new 
  material 
  shows 
  that 
  instead 
  of 
  

   being 
  conspecific 
  with 
  Pt. 
  acutus, 
  as 
  Wachsmuth 
  and 
  Springer 
  26 
  

   thought 
  it 
  might 
  be, 
  this 
  form 
  is 
  a 
  very 
  well 
  marked 
  variation 
  of 
  the 
  

   type 
  of 
  Pt. 
  depressus, 
  from 
  which 
  it 
  is 
  distinguishable, 
  as 
  the 
  authors 
  

   pointed 
  out, 
  by 
  the 
  characters 
  of 
  the 
  base. 
  

  

  Horizon 
  and 
  locality. 
  — 
  Mississippian, 
  Upper 
  Chester, 
  Glen 
  Dean 
  

   formation; 
  Falls 
  of 
  Rough 
  Creek, 
  Breckinridge 
  County, 
  Kentucky. 
  

  

  26 
  North 
  Amer. 
  Crin. 
  Cam., 
  1897, 
  p. 
  70. 
  

   29 
  Idem, 
  p. 
  801. 
  

  

  