Vol.  49.] 
OF  THE  GENUS  ASTROCCENIA. 
571 
are  thick  and  simple  ;  coenenchyma  rare  between  them.  The  calices 
are  polygonal,  irregular  or  regular  in  shape  and  size,  and  their 
margins  are  ordinarily  simple.”  After  defining  the  columella  and 
septa,  he  concludes  thus  : — “  Gemmation  marginal  and  lateral,  or 
marginal  and  circumferential  only”  (p.  120). 
In  a  paper  on  the  so-called  Astrocoenice  from  the  South  Wales 
Conglomerate,  by  the  same  author,  which  was  published  in  this 
Journal  in  1886, 1  are  many  scattered  remarks  on  the  characteristics 
'of  the  genus,  to  which  reference  must  be  made.  These  are  the  most 
recent  observations  which  have  come  to  my  knowledge,  but  their 
value  is  unfortunately  much  lessened  by  the  highly  controversial 
nature  of  the  paper  in  which  they  occur.  The  polygonal  form  of  the 
corallites  is  strongly  insisted  upon,  and  the  greater  number  of  species 
are  specially  mentioned  as  having  no  structure  whatever  between 
the  walls,  which  are  united.  The  concluding  remarks  I  transcribe 
verbatim : — “  It  appears  that,  owing  to  greater  or  less  vigour  of 
growfih  and  to  the  influence  of  crowding,  the  corallites  may  be 
perfect  hexagonal  prisms,  or  irregularly  polygonal  in  transverse 
section,  and  that  the  walls  of  corallites  in  the  same  corallum  may 
be  very  thin  at  the  calicular  surface  and  thick  lower  down,  or 
thick  at  the  calicular  surface  and  forming  with  their  joined  neigh¬ 
bours  a  mural  or  intercalieular  coenenchyma  of  varying  width  ” 
(p.  110).  Then  follows  a  footnote  in  which  it  is  stated  that  the 
coenenchyma  “  resembles  that  of  Pocillopora  and  some  of  the  Oculi- 
nidse,  especially  of  the  base  of  AmphiJielia  and  the  stem  of 
Astrohelia ,”  and  “is  totally  distinct  from  the  intermural  coen¬ 
enchyma  of  such  forms  as  the  Stylinaceae.” 
W7ith  such  great  discrepancies  in  generic  definition  as  appear  in 
the  foregoing,  there  need  be  no  surprise  if  a  somewhat  mixed 
assemblage  of  forms  are  found  accumulated  under  one  name,  and  it 
was  with  a  view  to  clear  up  the  confusion  that  the  following  inves¬ 
tigations  were  made. 
I  much  regret  that  I  have  been  unable  to  examine  specimens  of 
the  type  species,  A.strocoenia  cT Orbignyi,  but  with  the  kind  aid  of 
jny  friend  Mr.  11.  Etheridge,  F.R.S.,  who  has  had  sections  prepared 
for  me,  and  otherwise  afforded  me  valuable  assistance,  I  have 
examined  the  internal  structure  of  Astroccenici  decapliyUa,  A.  reticu¬ 
lata,  A.  tuberculata,  A.  rcimosa,  and  A.  tourtiensis,  Bolsche.  Only 
very  partial  success  attended  my  efforts  at  first,  the  Gosau  specimens 
not  showing  their  structure  very  clearly.  But  the  last-named  species 
has  proved  to  be  in  a  very  satisfactory  state  of  preservation,  and  the 
details  of  its  structure  could  be  examined  with  certainty.  I  commence 
therefore  with  that  species,  and  speak  of  the  others  afterwards. 
Astroccenia  tourtiensis,  Bolsche.' 
A  large  piece  of  a  specimen  from  Plauen,  for  which  I  am  indebted 
to  the  original  describer,  Dr.  Bolsche,  was  cut  into  thin  slices  and 
examined  by  transmitted  light,  and  its  details  of  structure  were  then 
seen  most  beautifully.  The  first  thing  observable  is  that  the  walls 
of  the  prismatic  corallites  are  invariably  thin,  sometimes  rudimentary 
1  Yol.  xlii.  pp.  101-111. 
-  •  -  /  ,? 
