Vol.  49.]  MADREPORARIA  PROM  THE  SUTTON  STONE.  575 
both  generically  and  specifically,  by  the  Rev.  H.  H.  Winwood,  and 
is  the  larger  specimen  on  the  tablet.  One  part  is  dark  in  colour, 
having  been  discoloured  by  exposure  to  the  elements,  while  the  other 
part  appears  to  have  been  freed  from  the  matrix  by  the  collector, 
and  is  quite  light  in  colour.  On  the  dark  and  weathered  portion 
there  is  a  distinct  and  raised  space  in  the  triangular  interval  where 
three  calices  meet,  on  which  are  indications  of  septa,  being  the 
commencement  of  a  calice.  This  is  so  placed  between  the  large 
calices,  and  so  much  above  their  level,  as  to  leave  no  doubt  that 
extra-calicular  gemmation  took  place  just  as  in  Stylocoenia  and 
Batliycoenia.  There  are  several  other  small  calices  on  the  light- 
coloured  part  of  the  corallum  similarly  placed  with  respect  to  the 
larger  ones,  which  are  also  very  striking  and  conclusive,  and  are 
evidently  the  result  of  gemmation.  Elongated  and  undoubtedly 
fissiparous  calices  also  appear  in  places  on  the  corallum,  but  they  do 
not  show  division  actually  taking  place  so  clearly  as  do  some  similar 
ones  in  another  specimen  to  which  I  shall  presently  refer.  Nowhere 
on  this  specimen  is  there  the  faintest  indication  of  a  calicular  wall, 
but  there  is  obvious  continuity  of  the  septa  between  the  calices  ; 
indeed,  there  is  in  this  specimen  a  remarkable  departure  from  any 
of  the  characters  hitherto  assigned  to  any  of  the  Sutton  Stone 
Madreporaria. 
The  remaining  recognized  specimen  was  taken  by  me  from  the 
Sutton  Stone  in  1883,  but  has  remained  undetermined  until  the 
present  time.  It  is  small,  barely  1  inch  in  diameter,  but,  being  freed 
from  the  matrix,  exhibits  the  form  of  the  corallum  with  certainty. 
It  may  be  described  as  tuber-shaped,  with  some  gibbosities,  and  was 
attached  by  a  small  space  on  one  of  the  longer  sides.  Excepting 
that  it  has  a  great  number  of  small  round  calices  scattered  between 
the  larger  ones,  undoubtedly  the  consequence  of  budding,  and  that 
it  exhibits  fissiparous  increase  of  the  calices  at  one  place,  it  is  less 
instructive  than  the  other. 
I  now  come  to  the  examination  of  the  thin  section,  taken  from  the 
specimen  in  the  Museum  of  the  Geological  Society,  having  the  polished 
surface  which  was  figured  by  Prof.  Duncan.  This  specimen,  like 
the  other  two,  has  small  rounded  calices  in  the  intervals  between  the 
larger  and  more  angular  ones,  which  are  highly  suggestive  of  extra- 
calicular  gemmation.  The  elongated  or  double  calices,  figured  by 
Prof.  Duncan  as  instances  of  inter-calicular  gemmation  and  as 
affording  evidence  of  Astrocoenian  relationship,  are  undoubtedly  the 
result  of  fissiparous  increase.  Of  the  apparently  extremely  thick 
walls  but  little  could  be  determined  until  they  were  examined  by 
transmitted  light ;  neither  could  the  nature  of  the  ornamentation 
on  the  sides  of  the  septa,  shown  by  fig.  9  1  of  Prof.  Duncan’s  plate, 
be  any  better  understood.  When,  however,  these  parts  were  seen 
in  thin  section,  the  nature  of  both  became  apparent. 
I  will  now  proceed  to  give  more  in  detail  the  results  of  my 
examination  of  the  section  just  mentioned,  without  which  the  real 
1  Quart.  Journ.  Geol.  Soc.  vol.  xlii,  (1886)  pi.  viii. 
Q,.  J.  G.  S.  No.  196.  2  o, 
