﻿94 
  PROCEEDINGS 
  OP 
  THE 
  NATIONAL, 
  MUSEUM 
  vol.67 
  

  

  constructed 
  arms 
  and 
  pinnules, 
  so 
  characteristic 
  of 
  the 
  great 
  Si- 
  

   lurian 
  and 
  Carboniferous 
  crinoid 
  deposits 
  of 
  Europe 
  and 
  America, 
  

   are 
  but 
  little 
  represented 
  in 
  Timor; 
  although 
  there 
  were 
  evidently 
  

   some 
  areas 
  of 
  quiet 
  water 
  protected 
  from 
  wave 
  action, 
  as 
  on 
  the 
  

   lee 
  side 
  of 
  reefs, 
  which 
  accommodated 
  species 
  with 
  thin 
  stems, 
  

   especially 
  the 
  multitudes 
  of 
  blastoids, 
  of 
  which 
  there 
  have 
  been 
  

   collected, 
  belonging 
  to 
  a 
  single 
  genus, 
  upwards 
  of 
  60,000 
  specimens. 
  

   The 
  crinoids, 
  now 
  largely 
  imbedded 
  in 
  marls 
  and 
  volcanic 
  tufas, 
  

   have 
  been 
  much 
  broken 
  up 
  by 
  action 
  of 
  rough 
  water, 
  transporta- 
  

   tion 
  from 
  their 
  original 
  habitat, 
  and 
  by 
  subsequent 
  geological 
  move- 
  

   ments, 
  so 
  that 
  complete 
  specimens 
  are 
  rare 
  ; 
  and 
  mam^ 
  strong 
  isolated 
  

   stem 
  fragments 
  are 
  present, 
  indicating 
  the 
  existence 
  of 
  forms 
  of 
  

   which 
  the 
  other 
  parts 
  have 
  disappeared. 
  

  

  The 
  most 
  remarkable 
  modification 
  caused 
  by 
  the 
  life 
  conditions 
  was 
  

   the 
  reduction 
  and 
  loss 
  of 
  arms, 
  thought 
  to 
  be 
  due 
  to 
  the 
  action 
  of 
  cur- 
  

   rents 
  bringing 
  the 
  food 
  directly 
  to 
  the 
  stationary 
  crinoids 
  without 
  

   the 
  aid 
  of 
  moving 
  arms, 
  which 
  through 
  atrophy 
  from 
  disuse 
  were 
  

   reduced 
  in 
  number, 
  even 
  finally 
  to 
  complete 
  suppression. 
  There 
  

   are 
  9 
  genera 
  of 
  such 
  forms 
  occurring 
  here, 
  two 
  of 
  them 
  before 
  des- 
  

   cribed 
  from 
  other 
  areas, 
  while 
  7 
  are 
  new 
  and 
  restricted 
  to 
  Timor. 
  

   Two 
  of 
  these 
  have 
  3 
  arm-bearing 
  rays, 
  three 
  have 
  only 
  one, 
  and 
  in 
  

   the 
  remaining 
  four 
  all 
  the 
  arms 
  have 
  disappeared. 
  The 
  latter 
  must 
  

   represent 
  a 
  persistent 
  larval 
  condition, 
  being 
  composed 
  of 
  the 
  prim- 
  

   ative 
  elements 
  of 
  the 
  crinoid 
  skeleton, 
  namely, 
  basals 
  and 
  orals. 
  

   with 
  the 
  addition 
  of 
  well 
  developed 
  infrabasals, 
  and 
  in 
  one 
  case 
  

   of 
  rudimentary 
  radials. 
  Some 
  of 
  the 
  specimens 
  bear 
  a 
  striking 
  re- 
  

   semblance 
  to 
  the 
  larval 
  Comactinia. 
  as 
  illustrated 
  on 
  plate 
  B 
  of 
  my 
  

   work 
  on 
  the 
  Crinoidea 
  Flexibilia. 
  

  

  While 
  the 
  absence 
  of 
  arms 
  is 
  the 
  predominating 
  character, 
  the 
  

   four 
  genera 
  are 
  separated 
  by 
  differences 
  readily 
  recognized, 
  which 
  

   emphasize 
  the 
  extreme 
  modifications 
  produced 
  by 
  the 
  conditions 
  

   under 
  which 
  they 
  existed. 
  For 
  example, 
  one 
  of 
  the 
  genera, 
  appro- 
  

   priately 
  named 
  Embryocrinus* 
  has 
  radials 
  upon 
  which 
  the 
  arms 
  

   might 
  potentially 
  have 
  grown, 
  but 
  did 
  not; 
  they 
  are 
  very 
  small, 
  

   rudimentary, 
  and 
  not 
  in 
  contact 
  — 
  substantially 
  as 
  in 
  the 
  early 
  stage 
  

   of 
  the 
  Comactinia 
  larva. 
  But 
  in 
  the 
  other 
  three 
  there 
  is 
  no 
  trace 
  

   or 
  vestige 
  of 
  radials, 
  the 
  interval 
  between 
  basals 
  and 
  orals, 
  where 
  

   the 
  radials 
  normally 
  originate, 
  being 
  shut 
  off 
  by 
  the 
  close 
  contact 
  

   of 
  those 
  plates. 
  In 
  one 
  of 
  these, 
  Lageniocrinus, 
  the 
  orals 
  are 
  inter- 
  

   radial 
  in 
  position, 
  in 
  line 
  with 
  the 
  basals 
  — 
  being 
  the 
  normal 
  loca- 
  

   tion 
  in 
  crinoids 
  generally 
  — 
  which 
  theoretically 
  would 
  leave 
  a 
  place 
  

   at 
  the 
  corners 
  for 
  arms 
  to 
  develop 
  ; 
  but 
  in 
  the 
  other 
  two, 
  Coenocystis 
  

   and 
  Acariaiocrinus, 
  they 
  are 
  radial, 
  alternating 
  with 
  the 
  basals 
  — 
  

   an 
  unprecedented 
  arrangement 
  which 
  would 
  exclude 
  every 
  possi- 
  

   bility, 
  actual 
  or 
  theoretical, 
  of 
  the 
  development 
  of 
  arms. 
  Two 
  of 
  

  

  