﻿PLATE 
  VI. 
  

  

  LlCHENALIA 
  CONCENTRICA 
  Ball. 
  

  

  Page 
  116. 
  

  

  Figs. 
  1, 
  2. 
  The 
  upper 
  and 
  lower 
  surfaces 
  of 
  a 
  young 
  specimen, 
  the 
  latter 
  showing 
  

  

  a 
  small 
  cicatrice 
  of 
  attachment. 
  

   Fig. 
  4. 
  The 
  under 
  surface 
  of 
  a 
  specimen, 
  showing 
  the 
  epitheca 
  in 
  its 
  irregular 
  

  

  growth, 
  and 
  its 
  strong 
  concentric 
  markings. 
  

   Fig. 
  7. 
  A 
  fragment 
  of 
  Fenestella, 
  having 
  two 
  young 
  specimens 
  of 
  Lichenalia 
  

  

  attached 
  to 
  the 
  surface. 
  

   Fig. 
  8. 
  The 
  lower 
  surface 
  of 
  a 
  small 
  fragment 
  with 
  scarcely 
  any 
  remaining 
  

  

  epitheca, 
  and 
  so 
  translucent 
  that 
  the 
  structure 
  is 
  visible 
  through 
  

  

  the 
  substance, 
  showing 
  the 
  elongated 
  cell-bases. 
  

   Fig. 
  9. 
  The 
  lower 
  surface 
  of 
  a 
  specimen 
  corresponding 
  to 
  fig. 
  3, 
  showing 
  the 
  

  

  concentric 
  markings 
  of 
  the 
  epitheca. 
  

   Fig. 
  10. 
  The 
  lower 
  surface 
  of 
  a 
  small 
  specimen 
  where 
  the 
  epitheca 
  has 
  been 
  

  

  worn 
  away 
  or 
  only 
  partially 
  developed, 
  showing 
  along 
  the 
  base, 
  

  

  the 
  radiating 
  grooves 
  formed 
  by 
  the 
  cells 
  before 
  curving 
  upward 
  

  

  toward 
  the 
  surface. 
  

  

  Lichenalia 
  concentrica 
  var. 
  maculata 
  n. 
  var. 
  

  

  Page 
  117. 
  

  

  Fig. 
  3. 
  The 
  upper 
  or 
  celluliferous 
  surface 
  of 
  a 
  regularly 
  growing 
  specimen 
  of 
  

   medium 
  size, 
  showing 
  tubercles 
  with 
  maculae 
  of 
  larger 
  cells. 
  The 
  

   cells 
  are 
  represented 
  much 
  larger 
  than 
  they 
  really 
  are 
  on 
  the 
  

   specimen. 
  (See 
  fig. 
  5.) 
  

  

  Fig. 
  5. 
  A 
  small 
  irregular 
  specimen, 
  with 
  unusually 
  distinct 
  maculee 
  upon 
  the 
  

   celluliferous 
  surface. 
  

  

  Fig. 
  6. 
  An 
  enlargement 
  from 
  a 
  part 
  of 
  the 
  surface 
  of 
  specimen 
  fig. 
  3, 
  where 
  it 
  

   has 
  been 
  worn 
  or 
  macerated, 
  showing 
  the 
  angular 
  intercellular 
  

   spaces. 
  - 
  x 
  

  

  