﻿152 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Found 
  in 
  the 
  Rochester 
  shale 
  at 
  Lockport 
  (Hall). 
  Isolated 
  frag- 
  

   ments 
  of 
  plates 
  have 
  been 
  obtained 
  from 
  the 
  weathered 
  lower 
  

   Rochester 
  shale 
  in 
  the 
  Niagara 
  gorge. 
  

  

  Class 
  CRINOIDEA 
  Miller 
  

  

  The 
  crinoids, 
  or 
  sea 
  lilies, 
  are 
  marine 
  invertebrates, 
  represented 
  

   in 
  the 
  modern 
  seas 
  by 
  a 
  number 
  of 
  genera 
  and 
  species 
  which 
  range 
  

   from 
  shallow 
  water 
  to 
  a 
  maximum 
  depth 
  of 
  about 
  3000 
  fathoms. 
  

   They 
  are 
  gregarious 
  in 
  habit, 
  and 
  usually 
  of 
  very 
  local 
  distribution. 
  

   A 
  typical 
  crinoid 
  consists 
  of 
  a 
  dorsal 
  cup 
  or 
  calyx, 
  placed 
  on 
  a 
  stalk 
  

   or 
  stem, 
  by 
  means 
  of 
  which 
  it 
  is 
  attached, 
  and 
  bears 
  a 
  fringe 
  of 
  arms, 
  

   variously 
  divided 
  and 
  furnished 
  with 
  jointed 
  appendages, 
  or 
  pin- 
  

   nules. 
  The 
  calyx 
  is 
  composed 
  of 
  a 
  number 
  of 
  plates, 
  which 
  have 
  a 
  

   definite 
  arrangement, 
  in 
  horizontally 
  disposed 
  series 
  (fig. 
  50). 
  The 
  

   lowest 
  of 
  these 
  are 
  the 
  basals, 
  though 
  in 
  many 
  forms 
  an 
  additional 
  

   -series, 
  the 
  infrabasals, 
  may 
  underlie 
  and 
  alternate 
  with 
  the 
  basals. 
  

   Next 
  above 
  the 
  basals, 
  and 
  alternating 
  with 
  them 
  in 
  position, 
  are 
  

   the 
  radials, 
  five 
  in 
  number, 
  so 
  called 
  because 
  they 
  are 
  in 
  line 
  with 
  

   the 
  rays 
  or 
  arms. 
  Referring 
  the 
  position 
  of 
  the 
  inferior 
  plates 
  to 
  

   that 
  of 
  the 
  radials, 
  we 
  find 
  that 
  the 
  basals 
  are 
  always 
  situated 
  inter- 
  

   radially, 
  while 
  the 
  infrabasal 
  are 
  situated 
  radially. 
  Above 
  the 
  

   radials 
  lie 
  the 
  brachials. 
  These 
  vary 
  greatly 
  in 
  number 
  and 
  kind, 
  

   .sometimes 
  articulating 
  directly 
  with 
  the 
  radials, 
  in 
  which 
  case 
  all 
  

   the 
  brachials 
  are 
  free, 
  and 
  sometimes 
  having 
  their 
  lower 
  series 
  fixed 
  

   and 
  immovable, 
  thus 
  forming 
  a 
  part 
  of 
  the 
  calyx. 
  The 
  brachials 
  

   lying 
  directly 
  on 
  the 
  radials 
  are 
  the 
  costals; 
  of 
  these 
  there 
  may 
  be 
  

   one 
  or 
  more 
  series, 
  when 
  they 
  are 
  distinguished 
  from, 
  below 
  as 
  

   primary 
  (cost.^), 
  secondary 
  (cost.^), 
  etc. 
  The 
  uppermost 
  costal 
  of 
  

   ■each 
  ray 
  is 
  commonly 
  axillary, 
  i. 
  e. 
  pentagonal 
  in 
  outline, 
  with 
  two 
  

   upper 
  joint 
  edges 
  inclined 
  from 
  each 
  other. 
  On 
  these 
  rest 
  the 
  

   distichals, 
  of 
  which 
  there 
  are 
  10 
  in 
  each 
  series. 
  Secondary 
  distichals 
  

   (dist.2) 
  may 
  rest 
  on 
  the 
  primary 
  ones 
  (dist.^), 
  and 
  may 
  in 
  turn 
  sup- 
  

   port 
  the 
  palmars, 
  of 
  which 
  there 
  would 
  be 
  20 
  in 
  a 
  normal 
  series. 
  

   Above 
  these, 
  on 
  farther 
  division, 
  are 
  the 
  post-palmars, 
  which 
  are 
  

   often 
  very 
  numerous. 
  Two 
  types 
  of 
  arms 
  can 
  be 
  distinguished, 
  

   those 
  composed 
  throughout 
  of 
  one 
  series 
  of 
  plates 
  (uniserial), 
  and 
  

   those 
  made 
  up 
  of 
  a 
  double 
  series 
  (biserial), 
  the 
  plates 
  of 
  the 
  latter 
  

   nsually 
  interlocking 
  to 
  a 
  greater 
  or 
  less 
  extent. 
  The 
  latter 
  are 
  the 
  

   more 
  specialized, 
  always 
  beginning 
  uniserially. 
  

  

  Between 
  the 
  radials 
  are 
  often 
  found 
  additional 
  plates, 
  the 
  inte?-- 
  

   radials, 
  which 
  may 
  vary 
  in 
  number. 
  

  

  Between 
  the 
  distichals 
  of 
  one 
  ray 
  may 
  occur 
  the 
  inter 
  distichals, 
  

   which 
  are 
  situated 
  radially. 
  Between 
  the 
  distichals 
  of 
  adjacent 
  rays 
  

   may 
  occur 
  the 
  interbrachials, 
  and 
  these 
  will 
  be 
  situated 
  interradially. 
  

  

  