﻿176. 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Genus 
  lichenalia 
  Hall 
  

  

  [Ety. 
  : 
  IzixTiv, 
  lichen] 
  

  

  (1852. 
  Pal 
  iV. 
  Y. 
  2:171) 
  

  

  Zoarium 
  a 
  subcircular 
  expansion, 
  consisting 
  of 
  a 
  single 
  lamina^ 
  

   but 
  often 
  growing 
  in 
  successive 
  layers, 
  the 
  one 
  over 
  the 
  other; 
  

   zooecia 
  prostrate, 
  elongate 
  subrhomboidal, 
  with 
  a 
  direct, 
  subtubular, 
  

   outward 
  prolongation 
  or 
  vestibule; 
  apertures 
  rounded, 
  with 
  the 
  

   peristome 
  much 
  elevated 
  on 
  the 
  posterior 
  side; 
  interspaces 
  de- 
  

   pressed. 
  

  

  Lichenalia 
  concentrica 
  Hall 
  (Fig. 
  79) 
  (1852. 
  Pal. 
  N. 
  Y. 
  2:171, 
  

   pi. 
  37A, 
  fig. 
  2a, 
  b) 
  

  

  Distinguishing 
  characters. 
  Circular 
  frond, 
  slightly 
  cup-form 
  in 
  the 
  

   young 
  state, 
  flattened 
  at 
  maturity; 
  generally 
  variously 
  contorted 
  

   from 
  irregular 
  growth 
  or 
  accident, 
  and 
  thick 
  at 
  intervals; 
  concen- 
  

  

  Fig. 
  79 
  Lichenalia 
  concentrica 
  

  

  trically 
  striate 
  and 
  rugose 
  surface, 
  strongest 
  on 
  non-celluliferous 
  

   side; 
  apertures 
  in 
  concentric 
  lines, 
  narrow, 
  opening 
  on 
  the 
  summit 
  

   of 
  an 
  elevated 
  pustule. 
  

  

  Found 
  rarely 
  in 
  the 
  lower 
  Clinton 
  limestone; 
  abundantly 
  in 
  the 
  

   Clinton 
  lenses; 
  and 
  again 
  rarely 
  in 
  the 
  lower 
  Rochester 
  shale 
  and 
  

   the 
  Bryozoa 
  bed. 
  Niagara 
  sections. 
  Also 
  at 
  Lockport 
  and 
  else- 
  

   where 
  (Hall). 
  

  

  