﻿The 
  Fauna 
  of 
  the 
  Niagara 
  Group. 
  197 
  

  

  LICHAS 
  Dalman. 
  

  

  LlCHAS 
  BREVICEPS. 
  

  

  Plate 
  34, 
  Figs. 
  1-7. 
  

  

  Lichas 
  breviceps 
  Hall. 
  Trans. 
  Alb. 
  Inst., 
  vol. 
  iv, 
  p. 
  222. 
  Abstract, 
  p. 
  28; 
  May, 
  

  

  1863. 
  

   Not 
  Lichas 
  breviceps 
  ? 
  Hall. 
  20th 
  Rep. 
  St. 
  Cab. 
  Nat. 
  Hist., 
  pp. 
  334, 
  377, 
  pi. 
  21, 
  

  

  figs. 
  12-14. 
  Rev. 
  Edit., 
  p. 
  424. 
  

  

  Head 
  broad 
  and 
  short, 
  somewhat 
  crescentiform, 
  projecting 
  

   in 
  front 
  and 
  prominent 
  in 
  the 
  middle, 
  the 
  length 
  about 
  one- 
  

   third 
  as 
  great 
  as 
  the 
  width, 
  posterior 
  angles 
  directed 
  back- 
  

   ward 
  in 
  short 
  obtuse 
  spines. 
  Glabella 
  very 
  convex, 
  wider 
  

   than 
  long, 
  rounded 
  in 
  front, 
  distinctly 
  divided 
  into 
  three 
  lobes, 
  

   two 
  lateral 
  and 
  one 
  central, 
  the 
  central 
  lobe 
  narrower 
  behind 
  

   and 
  rapidly 
  expanding 
  in 
  front, 
  the 
  lateral 
  lobes 
  reniform 
  and 
  

   about 
  as 
  wide 
  as 
  the 
  posterior 
  part 
  of 
  the 
  central 
  or 
  anterior 
  

   lobe, 
  commencing 
  forward 
  of 
  the 
  eye 
  and 
  reaching 
  to 
  the 
  occi- 
  

   pital 
  furrow. 
  Eyes 
  very 
  prominent, 
  reniform, 
  very 
  convex 
  on 
  

   the 
  visual 
  surface, 
  having 
  the 
  appearacce 
  of 
  the 
  eyes 
  in 
  II- 
  

   ljenus. 
  Anterior 
  border 
  of 
  the 
  head 
  very 
  narrow 
  in 
  front 
  of 
  

   the 
  glabella, 
  being 
  only 
  a 
  rounded 
  rim. 
  Cheeks 
  flat 
  or 
  slightly 
  

   concave, 
  with 
  a 
  prominently 
  rounded 
  ridge 
  just 
  beneath 
  the 
  

   eye. 
  Occipital 
  ring 
  prominent 
  ; 
  furrow 
  deep, 
  becoming 
  very 
  

   faint 
  in 
  its 
  extension 
  into 
  the 
  cheek 
  furrows. 
  Surface 
  of 
  the 
  

   head 
  marked 
  by 
  fine 
  scabrous 
  pustules. 
  

  

  A 
  portion 
  of 
  the 
  thorax 
  connected 
  with 
  a 
  pygidium 
  pre- 
  

   serves 
  the 
  remains 
  of 
  ten 
  articulations, 
  in 
  one 
  of 
  the 
  lateral 
  

   lobes 
  and 
  on 
  a 
  part 
  of 
  the 
  axial 
  lobe. 
  The 
  axial 
  lobe 
  is 
  

   wider 
  in 
  the 
  middle 
  than 
  at 
  its 
  junction 
  with 
  the 
  head, 
  and 
  

   from 
  the 
  seventh 
  articulation 
  gradually 
  tapers 
  to 
  the 
  pygidium. 
  

   The 
  lateral 
  lobe 
  is 
  a 
  little 
  more 
  than 
  two-thirds 
  as 
  wide 
  as 
  

   the 
  axial 
  lobe 
  in 
  its 
  greatest 
  width 
  ; 
  the 
  articulations 
  are 
  

   somewhat 
  abruptly 
  turned 
  backward 
  toward 
  their 
  extremi- 
  

   ties, 
  which 
  are 
  closely 
  arranged 
  and 
  in 
  contact, 
  except 
  the 
  last 
  

   one, 
  between 
  which 
  and 
  the 
  first 
  segment 
  of 
  the 
  pygidium 
  is 
  

   a 
  narrow 
  free 
  space. 
  

  

  The 
  separated 
  pygidia 
  present 
  the 
  following 
  characters 
  : 
  

   General 
  form 
  semi-elliptical, 
  a 
  little 
  rounded 
  on 
  the 
  anterior 
  

   border 
  ; 
  axial 
  lobe 
  broad 
  and 
  strong, 
  very 
  prominent 
  in 
  the 
  

   anterior 
  part, 
  rapidly 
  narrowing 
  and 
  becoming 
  low 
  in 
  the 
  

  

  