﻿4£ 
  A. 
  F. 
  Foerste 
  — 
  Relations 
  of 
  the 
  

  

  rows 
  do 
  not 
  reach 
  the 
  occipital 
  furrow 
  but 
  terminate 
  at 
  a 
  

   considerable 
  distance 
  from 
  the 
  latter, 
  with 
  a 
  short, 
  out- 
  

   wardly 
  directed 
  curve, 
  ending 
  in 
  a 
  sort 
  of 
  pit. 
  In 
  one 
  

   specimen 
  a 
  second 
  pit 
  occurred 
  in 
  the 
  glabellar 
  furrow, 
  

   about 
  half 
  way 
  between 
  the 
  posterior 
  end 
  of 
  the 
  furrow 
  

   and 
  the 
  frontal 
  border. 
  Interpreting 
  the 
  anterior 
  one 
  of 
  

   these 
  pits 
  as 
  the 
  inner 
  end 
  of 
  the 
  first 
  pair 
  of 
  glabellar 
  

   furrows, 
  and 
  the 
  posterior 
  pit 
  as 
  the 
  inner 
  part 
  of 
  the 
  

   second 
  pair 
  of 
  glabellar 
  furrows, 
  the 
  lobe 
  outlined 
  by 
  this 
  

   furrow 
  must 
  correspond 
  to 
  the 
  anterior 
  lateral 
  glabellar 
  

   lobe 
  of 
  other 
  Lichads, 
  and 
  the 
  space 
  intervening 
  between 
  

   the 
  posterior 
  margin 
  of 
  this 
  anterior 
  lobe 
  and 
  the 
  occip- 
  

   ital 
  ring 
  must 
  correspond 
  to 
  both 
  the 
  second 
  and 
  the 
  

   third 
  pair 
  of 
  lateral 
  glabellar 
  lobes 
  of 
  other 
  Lichads, 
  

   these 
  two 
  pairs 
  having 
  coalesced 
  in 
  the 
  specimens 
  at 
  

   hand. 
  This 
  would 
  agree 
  with 
  the 
  structure 
  of 
  most 
  

   other 
  Lichads 
  in 
  which 
  the 
  anterior 
  lateral 
  glabellar 
  

   lobes 
  are 
  the 
  largest, 
  and 
  the 
  posterior 
  pair 
  are 
  the 
  

   smallest 
  of 
  the 
  series. 
  

  

  It 
  is 
  possible 
  that 
  these 
  small 
  cranidia 
  do 
  not 
  belong 
  to 
  

   minganensis 
  but 
  represent 
  a 
  distinct 
  species. 
  In 
  analogy 
  

   with 
  Ampliiliclias, 
  the 
  young 
  of 
  Acrolichas 
  might 
  be 
  

   expected 
  to 
  be 
  characterized 
  by 
  glabellar 
  furrows 
  ending 
  

   abruptly 
  posteriorly 
  without 
  any 
  change 
  in 
  curvature 
  

   (producing 
  a 
  result 
  similar 
  to 
  that 
  figured 
  in 
  the 
  adult 
  of 
  

   Ampliiliclias 
  Icevis, 
  in 
  figure 
  HA, 
  on 
  Plate 
  IV). 
  

  

  Acrolichas 
  cli 
  am 
  plain 
  en 
  sis 
  (Whitfield), 
  PL 
  III, 
  fg. 
  3. 
  

   Raymond 
  (Ann. 
  Carnegie 
  Museum, 
  3, 
  1905, 
  p. 
  355) 
  refers 
  

   Lichas 
  cliamplainensis 
  to 
  the 
  species 
  minganensis. 
  In 
  

   Lichas 
  cliamplainensis, 
  however, 
  the 
  notch 
  between 
  the 
  

   tips 
  of 
  the 
  posterior' 
  pair 
  of 
  ribs 
  is 
  narrow, 
  while 
  in 
  the 
  

   pygidium 
  of 
  Liclias 
  minganensis 
  figured 
  by 
  Raymond 
  

   (PL 
  III, 
  fig. 
  1c) 
  the 
  tips 
  of 
  these 
  ribs 
  are 
  divergent. 
  Dif- 
  

   ferences 
  as 
  great 
  as 
  this 
  are 
  not 
  known 
  in 
  other 
  Lichadi- 
  

   dse 
  in 
  the 
  same 
  species. 
  Apparently 
  several 
  species 
  of 
  

   Lichads 
  exist 
  in 
  the 
  Chazyan 
  of 
  New 
  York, 
  which 
  have 
  

   not 
  yet 
  been 
  differentiated. 
  

  

  Acrolichas 
  cucullus, 
  PL 
  I, 
  figs. 
  1 
  AG. 
  The 
  genotype 
  

   of 
  Acrolichas 
  is 
  the 
  species 
  described 
  by 
  Meek 
  and 
  

   Worthen 
  from 
  the 
  Kimmswick 
  limestone 
  in 
  Alexander 
  

   county, 
  Illinois, 
  under 
  the 
  name 
  Lichas 
  cucullus. 
  The 
  

   type 
  specimen 
  was 
  a 
  well 
  preserved 
  cranidium, 
  and, 
  in 
  

   vol. 
  3 
  of 
  the 
  Geol. 
  Surv. 
  of 
  Illinois, 
  in 
  1868 
  (PL 
  1, 
  figs. 
  

   6a, 
  b, 
  c), 
  three 
  illustrations 
  are 
  presented 
  of 
  this 
  type, 
  

  

  