574 
ME.  E.  F.  TOMES  OX  A  NEW  GENUS  OF 
[Xov.  1893, 
43.  Description  of  0.  Xew  Genus  of  Maeeepoeaeia  from  the  Sutton 
Stone  of  South  Wales.  By  Bobert  E.  Tomes,  Esq.,  E.G.S. 
(Bead  June  21st,  1S93.) 
[Plate  XX.] 
In  vol.  xlii.  (1886)  of  this  Journal  is  a  critical  and  detailed  descrip¬ 
tion  of  a  coral  from  the  Sutton  Stone  of  South  Wales,  which  is  there 
described  as  Astrocoenia  gibhosa ,  Dune.  The  paper  in  which  it 
appears  is,  I  need  hardly  say,  by  the  late  Prof.  Duncan.  But  the 
specimen  there  described  is  not  the  type  of  the  species,  and,  indeed, 
I  do  not  know  whether  it  had  ever  been  specifically  determined  before 
the  publication  of  the  paper  above  alluded  to ;  certainly  there  is  no 
mention  of  it  in  the  pages  of  the  volume  of  the  Palaeontographical 
Society,  in  which  Astrocoenia  gibhosa  was  first  characterized.  It  was 
collected  by  E.  B.  Tawney,  is  now  in  the  Museum  of  the  Geological 
Society,  and  after  having  been  cut  through  horizontally  and  polished, 
was  described  by  Prof.  Duncan  in  the  paper  above  mentioned. 
A  very  hasty  examination  of  the  polished  surface  figured  by  Prof. 
Duncan  sufficed  to  assure  me  that  there  were  characters  which  neither 
he  nor  I  had  attributed  to  that  or  any  other  species  of  coral  from  the 
Glamorganshire  Conglomerate.  Some  of  the  elongated  or  double 
calices  presented  much  the  appearance  of  fissiparous  division,  and  I 
was  anxious  to  examine  them  by  means  of  thin  sections  and  trans¬ 
mitted  light,  and  at  the  same  time  to  learn  something  of  the  structure 
of  another  part,  the  (apparently)  much  thickened  w alls.  In  accordance 
with  mv  wish,  the  Society  had  a  section  made  and  submitted  to  me 
for  examination.  It  consists  of  a  slice  taken  horizontally  from  the 
bottom  of  the  specimen,  the  upper  surface,  which  was  figured  by 
Prof.  Duncan,  being  left  untouched.  This  section  proves  to  be  nearly 
all  that  could  be  desired,  and  exhibits  structures  which  are  directly 
at  variance  with  all  former  determinations  of  the  generic  relationship. 
The  corallites  having  more  or  less  of  a  radiating  arrangement,  are 
cut  through  at  all  angles,  and  consequently  give  sections  which  are 
transverse,  oblique,  and  even  longitudinal. 
It  is  always  unsatisfactory  to  have  to  found  a  genus  on  a  single 
species,  however  strongly  marked  its  characters  may  be,  on  account  of 
the  difficult}’  of  drawing  the  line  between  those  which  are  generic  and 
those  which  are  merely  specific  ;  and  still  less  satisfactory  is  it  to  do 
so  when  only  a  single  specimen  is  available.  I  have  long  hesitated 
to  make  use  of  the  only  known  specimen  for  such  a  purpose,  but 
fortunately  two  other  specimens  from  the  same  locality,  that  is,  from 
the  Sutton  Stone  of  Glamorganshire,  have  been  discovered.  One 
of  these  is  in  the  Museum  of  Practical  Geolog5’  in  Jermyn  Street, 
and  is  attached  to  the  same  tablet  as  the  specimen  of  Astrocoenia 
gibhosa  figured  by  Prof.  Duncan  in  pi.  v.  fig.  2  of  the  fourth  part  of 
his  ‘Supplement  to  the  History  of  British  Dossil  Corals.’  It  was 
presented  with  the  figured  specimen,  which  is  quite  distinct  from  it, 
