﻿198 
  'Twenty-eighth 
  Eeport 
  on 
  the 
  State 
  Museum. 
  

  

  middle 
  and 
  again 
  widening 
  posteriorly 
  ; 
  its 
  width 
  at 
  the 
  an- 
  

   terior 
  margin 
  being 
  about 
  one-third 
  as 
  great 
  as 
  the 
  whole 
  

   width 
  of 
  the 
  tail 
  ; 
  a 
  single 
  anterior 
  annulation. 
  Lateral 
  lobe 
  

   with 
  three 
  segments 
  on 
  each 
  side, 
  and 
  each 
  marked 
  by 
  a 
  broad, 
  

   shallow, 
  longitudinal 
  furrow 
  ; 
  at 
  the 
  posterior 
  side 
  of 
  the 
  two 
  

   anterior 
  ones, 
  the 
  margin 
  of 
  the 
  shield 
  is 
  slightly 
  indented, 
  

   below 
  this 
  it 
  is 
  entire, 
  with 
  a 
  regularly 
  curved 
  outline 
  ; 
  the 
  

   two 
  anterior 
  segments 
  are 
  curved 
  a 
  little 
  backward 
  and 
  their 
  

   extremities 
  free, 
  while 
  the 
  third 
  one 
  is 
  curved 
  first 
  outward 
  

   and 
  then 
  downward, 
  uniting 
  with 
  the 
  depressed 
  axial 
  lobe. 
  

   The 
  enfolding 
  of 
  the 
  crust 
  on 
  the 
  lower 
  side 
  extends 
  upward 
  

   about 
  three-fifths 
  of 
  the 
  length 
  of 
  the 
  tail, 
  and 
  is 
  strongly 
  but 
  

   distantly 
  lamellose-striate. 
  

  

  Exterior 
  surface 
  marked 
  by 
  pustules 
  of 
  moderate 
  size, 
  and 
  

   a 
  few 
  short 
  hollow 
  spines. 
  

  

  It 
  resembles 
  L. 
  (Platynotus) 
  Trentonensis 
  as 
  recognized 
  in 
  

   the 
  blue 
  shales 
  of 
  the 
  Hudson 
  river 
  group 
  of 
  Cincinnati, 
  in 
  

   the 
  prominent 
  eyes 
  ; 
  but 
  the 
  head 
  is 
  much 
  shorter 
  in 
  propor- 
  

   tion 
  to 
  its 
  width, 
  and 
  the 
  tail 
  is 
  broader 
  and 
  more 
  nearly 
  

   straight 
  on 
  the 
  anterior 
  margin. 
  

  

  Lichas 
  Boltoni 
  (Bigsby) 
  var. 
  occtdentalis. 
  

  

  Plate 
  34, 
  Figs. 
  8-11. 
  

  

  Lichas 
  Boltoni 
  var. 
  occidentalis 
  Hall. 
  Trans. 
  Alb. 
  Inst., 
  vol. 
  iv, 
  p. 
  223. 
  Ab- 
  

   stract, 
  p. 
  29 
  ; 
  May, 
  1863. 
  

   For 
  citations, 
  see 
  Pal. 
  N. 
  Y., 
  vol. 
  ii, 
  p. 
  311. 
  1852. 
  

  

  This 
  form 
  is 
  known 
  almost 
  entirety 
  from 
  the 
  pygidia, 
  most 
  

   of 
  the 
  specimens 
  being 
  in 
  an 
  imperfect 
  condition. 
  The 
  mid- 
  

   dle 
  lobe 
  of 
  the 
  pygiclium 
  is 
  short 
  and 
  the 
  articulations 
  are 
  

   more 
  prolonged 
  than 
  in 
  the 
  usual 
  forms 
  of 
  L. 
  Boltoni 
  in 
  the 
  

   Niagara 
  shales 
  of 
  New 
  York. 
  This 
  character, 
  however, 
  is 
  

   subject 
  to 
  some 
  variation, 
  even 
  among 
  collections 
  from 
  the 
  

   same 
  locality, 
  as 
  may 
  be 
  seen 
  by 
  comparing 
  the 
  figure 
  on 
  plate 
  

   69 
  with 
  lg 
  on 
  plate 
  70 
  of 
  vol. 
  ii, 
  Pal. 
  N. 
  Y. 
  

  

  A 
  specimen 
  of 
  the 
  right 
  cheek 
  indicates 
  that 
  the 
  head 
  was 
  

   longer 
  and 
  more 
  curved 
  on 
  the 
  posterior 
  margin. 
  

  

  In 
  some 
  of 
  the 
  New 
  York 
  specimens, 
  the 
  anterior 
  border 
  in 
  

   front 
  of 
  the 
  glabella 
  is 
  produced 
  into 
  abroad 
  subnasute 
  exten- 
  

   sion, 
  and 
  a 
  single 
  fragment, 
  of 
  what 
  appears 
  to 
  be 
  a 
  similar 
  

   but 
  more 
  extreme 
  anterior 
  prolongation 
  of 
  the 
  head, 
  has 
  been 
  

   found 
  at 
  Waldron 
  (figure 
  12 
  of 
  plate 
  34). 
  Should 
  this 
  be 
  

  

  