Vol.  49. J 
ANTHRACOPTERA  AND  ANTHRACOMYA. 
261 
Remarks. — This  is  a  well-marked  form  of  wide  distribution,  com¬ 
pressed  in  comparison  with,  its  other  proportions.  Some  of  my  speci¬ 
mens  show  distinct  bands  of  colour;  it  occurs  chiefly  in  ironstone- 
bands.  When  young  it  resembles  closely  Anthracomya  Phillipsii  in 
shape. 
Localities. — Soap  Vein,  South  AVales ;  Little  Mine  Ironstone, 
Penton  and  Longton  ;  Xew  Mine  Ironstone,  Biddulph. 
Anthracomya  Adamsii,  var.  expansa,  AATieelton  Hind.  (PI.  IX. 
figs-  2,  3.) 
.Anthracomya  Adamsii,  Ward,  Trans.  North  Staffs.  Inst.  Min.  &  Mech.  Eng. 
vol.  x.  (L890)  p.  125,  pi.  i.  fig.  2. 
Specific  Characters. — Shell  obliquely  subquadrate,  compressed 
and  expanded.  Hinge-line  straight.  Umbones  obtuse,  slightly 
raised  above  the  hinge-line,  contiguous,  situated  at  4-  distance  from 
the  anterior  end.  Cartilage  external.  Anterior  end  almost  obsolete, 
very  obtuse,  no  oblique  sulcus  ;  but  an  obtuse  diagonal  swelling 
starts  from  the  umbones,  where  it  is  most  pronounced  (the  thickest 
part  of  the  shell),  to  be  lost  rapidly  on  the  posterior  part  of 
the  shell.  This  posterior  part  is  flattened  and  expanded.  The 
anterior,  inferior,  and  posterior  borders  are  part  of  one  general 
curve  which  meets  the  superior  border  posteriorly  at  an  obtuse 
angle.  There  is  no  relic  of  a  byssal  notch.  The  left  valve  is 
the  more  tumid. 
Interior  same  as  in  Anthracomya  Adamsii. 
Exterior. —  Surface  with  fine  concentric  lines  and  bands  of 
growth.  Periostracum  much  wrinkled. 
Size. — Antero-posterior  measurement,  53  mm.  (2|  inches) ;  greatest 
dorso-ventral,  42  mm.  (1|  inch)  ;  from  side  to  side,  8  mm.  (IT  inch). 
Remarks. — This  shell  is  found  in  the  same  beds  with  the  previous 
species,  of  which  I  believe  it  to  be  a  variety.  A  very  large  form, 
65  mm.  (2-|  inches)  long,  and  measuring  55  mm.  (2-1  inches)  dorso- 
ventrally,  is  found  in  the  Xew  Mine  Ironstone,  Biddulph.  It  is 
distinguished  by  its  produced  and  rounded  inferior  border,  and 
obsolete  anterior  end.  It  looks  very  much  like  the  figure  of 
A.  dolabrata,  Sowerby,  op.  jam  cit. :  but  the  latter  has  its  anterior 
end  broken  off,  and  is  therefore  imperfect.  It  is  also  very  much 
more  convex  than  the  specimen  under  description. 
Localities. — Little  Mine  Ironstone,  Penton,  Longton,  and  Hanley  ; 
Xew  Mine  Ironstone,  Biddulph. 
Anthracomya  dolabrata.  (PI.  VIII.  figs.  9,  9  a,  10,  10  a ;  PI.  IX. 
figs.  1,  1  a,  4,  5.) 
Unio  dolabratus,  Sowerby,  Trans..  Geoi.  Soc.  ser.  2,  vol.  v.  pt.3,  pi.  xxxix.  fig.  9. 
Modiola  curtata.  Brown,  ‘  Fossil  Conchology,’  pi.  lxxii.  figs.  19,  20. 
A.  dolabrata,  Salter,  Geol.  Surv.  Mem.,  ‘Iron  Ores  of  South  Wales,’  p.  230, 
no  fig. 
Specific  Characters.  —  Shell  tumid,  equivalve,  transversely 
elongated.  Hinge-line  straight,  much  raised,  about  length  of  the 
shell.  Umbones  obtuse  and  gibbous,  raised  above  the  hinge-line, 
situated  at  I  length  of  the  hinge-line  from  the  anterior  end. 
