﻿56 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  67 
  

  

  division 
  to 
  the 
  end 
  of 
  the 
  Chester, 
  with 
  which 
  it 
  becomes 
  practically 
  

   extinct 
  — 
  a 
  single 
  species, 
  A. 
  carbonarius, 
  having 
  been 
  recognized 
  by 
  

   Worthen 
  from 
  an 
  isolated 
  fragment 
  in 
  the 
  Coal 
  Measures 
  of 
  Illi- 
  

   nois. 
  As 
  showing 
  the 
  broad 
  distribution 
  of 
  this 
  crinoid, 
  I 
  may 
  add 
  

   that 
  I 
  found 
  a 
  specimen 
  of 
  the 
  common 
  inf 
  rabasal 
  cup 
  at 
  Santa 
  Fe, 
  

   New 
  Mexico, 
  in 
  a 
  formation 
  on 
  the 
  flank 
  of 
  the 
  Rocky 
  Mountains 
  

   strongly 
  resembling 
  the 
  upper 
  Chester, 
  but 
  now 
  correlated 
  as 
  

   Pennsylvanian. 
  

  

  Fragmentary 
  specimens 
  consisting 
  of 
  the 
  detached 
  bases 
  occur 
  

   throughout 
  the 
  upper 
  Chester 
  by 
  the 
  hundreds 
  at 
  all 
  the 
  principal 
  

   localities 
  in 
  southern 
  Illinois, 
  Kentucky, 
  Tennessee, 
  Alabama, 
  Vir- 
  

   ginia, 
  Ohio, 
  and 
  Arkansas. 
  Complete 
  calices 
  are 
  rare, 
  and 
  very 
  few 
  

   have 
  been 
  seen 
  with 
  any 
  part 
  of 
  the 
  arms 
  attached 
  ; 
  but 
  I 
  have 
  been 
  

   fortunate 
  in 
  obtaining 
  several 
  of 
  these 
  in 
  condition 
  available 
  for 
  the 
  

   comparison 
  about 
  to 
  be 
  made. 
  

  

  One 
  of 
  the 
  generally 
  accepted 
  traditions 
  about 
  Agassizoc? 
  7 
  inus, 
  

   and 
  the 
  character 
  by 
  which 
  it 
  is 
  chiefly 
  known 
  and 
  most 
  frequently 
  

   referred 
  to 
  in 
  morphological 
  discussions, 
  is 
  that 
  it 
  was 
  a 
  stemless 
  

   crinoid, 
  at 
  least 
  in 
  the 
  adult 
  stage. 
  Shumard 
  describes 
  it 
  thus 
  in 
  

   the 
  Marcy 
  Report 
  : 
  

  

  In 
  young 
  individuals 
  the 
  division 
  of 
  the 
  pelvis 
  into 
  5 
  pieces 
  is 
  well 
  marked, 
  

   but 
  in 
  adult 
  age 
  they 
  are 
  usually 
  firmly 
  anchylosed 
  and 
  often 
  all 
  traces 
  of 
  

   sutures 
  obliterated. 
  

  

  This 
  has 
  been 
  adopted 
  as 
  a 
  settled 
  conclusion 
  by 
  Wachsmuth 
  and 
  

   Springer 
  and 
  authors 
  generally. 
  Nevertheless 
  the 
  known 
  facts 
  do 
  

   not 
  bear 
  out 
  this 
  dictum 
  without 
  qualification. 
  

  

  Among 
  250 
  specimens 
  of 
  detached 
  bases 
  from 
  the 
  Gasper 
  forma- 
  

   tion 
  at 
  Huntsville, 
  Alabama, 
  mostly 
  of 
  medium 
  size, 
  from 
  7 
  to 
  15 
  

   mm. 
  in 
  diameter, 
  about 
  200 
  have 
  the 
  infrabasals 
  anchylosed, 
  while 
  

   about 
  35 
  below 
  medium 
  size 
  and 
  15 
  of 
  medium 
  size 
  or 
  larger 
  have 
  

   traces 
  of 
  inf 
  rabasal 
  sutures 
  and 
  column 
  facet; 
  among 
  these 
  one 
  of 
  

   the 
  largest 
  in 
  all 
  the 
  collections, 
  20 
  mm. 
  in 
  width, 
  has 
  the 
  infrabasals 
  

   well 
  divided 
  on 
  the 
  inside 
  (compare 
  figures 
  21 
  and 
  23 
  on 
  plate 
  15 
  

   for 
  the 
  two 
  extremes). 
  From 
  the 
  same 
  formation 
  in 
  Breckinridge 
  

   County, 
  Kentucky, 
  there 
  are 
  about 
  70 
  specimens, 
  of 
  which 
  23 
  show 
  

   the 
  infrabasals 
  divided 
  at 
  the 
  inside, 
  18 
  at 
  the 
  outside 
  with 
  the 
  

   column 
  facet 
  traceable, 
  and 
  the 
  remainder 
  have 
  the 
  infrabasals 
  com- 
  

   pletely 
  anchylosed; 
  these 
  differences 
  are 
  not 
  strictly 
  related 
  to 
  size, 
  

   some 
  of 
  those 
  with 
  column 
  facet 
  present 
  being 
  among 
  the 
  larger. 
  

  

  Specimens 
  are 
  numerous 
  in 
  the 
  collections 
  from 
  the 
  Glen 
  Dean 
  

   formation 
  in 
  Grayson 
  and 
  Pulaski 
  counties, 
  Kentucky. 
  Out 
  of 
  up- 
  

   wards 
  of 
  200, 
  about 
  one- 
  fourth 
  (mostly 
  the 
  smaller 
  ones 
  but 
  also 
  

   some 
  of 
  above 
  medium 
  size) 
  show 
  infrabasal 
  sutures 
  on 
  the 
  inside; 
  

   some 
  of 
  fairly 
  average 
  size 
  have 
  the 
  infrabasals 
  distinctly 
  divided, 
  

  

  