Vol.  49.] 
ANTHRACOPTERA  AND  ANTHRACOMYA. 
255 
Size. — Length  of  hinge-line,  30  mm.  (1TU  inch)  ;  greatest  dorso- 
ventral  measurement,  25  mm.  (1  inch) ;  thickness,  12  mm.  (T7g  inch). 
Another  specimen :  length  of  hinge,  23  mm.  (1|-  inch) ;  dorso- 
ventral  measurement,  25  mm.  (1  inch) ;  thickness,  5  mm.  (-i-  inch). 
Localities. — North  Staffordshire  :  Hard  Mine,  Ten-foot,  and  Ban¬ 
bury  Seams;  Coalbrookdale  :  White  Flats;  South  Wales:  Darran 
Pins ;  Bunker’s  Hill,  W.  of  Rochdale,  30  feet  below  the  Arley  Mine. 
Remarks. — This  species  is  easily  distinguished  from  others.  It  is 
somewhat  rare ;  but  its  flat,  peculiar  U-shaped  form,  and  expanding 
posterior  side,  separate  it  from  all  others.  The  oblique  ridge,  too, 
is  occasionally  nearly  at  a  right  angle  to  the  hinge-line,  but  mostly 
at  a  very  obtuse  angle.  A  series  of  specimens  with  slight  variations 
show  the  close  connexion  of  this  form  and  Anthracoptera  mocliolaris. 
Anthracoptera  temida.  (PI.  VII.  fig.  13,  13  a,  14.) 
R.  Etheridge,  Jun.,  Mem.  Geol.  Surv.  Scot.  Expl.  Sheet  31,  p.  82,  no  figure. 
Specific  Characters. — Transverse,  triangular,  gibbous,  with  strong 
diagonal  ridge,  dividing  the  valves  into  two  nearly  equal  parts. 
Anterior  side  well  marked,  tumid.  Sinuated  border,  with  byssal 
notch  most  marked  in  the  left  valve.  The  posterior  end  is  obliquely 
truncate,  the  margin  with  the  hinge-line  forming  an  obtuse  angle, 
occasionally  emarginate.  Hinge-line  shorter  than  length  of  shell ; 
lower  margin  obtusely  rounded.  Diagonal  ridge  and  umbonal 
region  very  convex,  forming  the  most  gibbous  part  of  the  shell. 
Ridge  almost  median,  rather  (if  anything)  anterior,  curved  forwards 
along  the  hinge-line,  to  become  almost  terminal.  Beaks  prominent, 
separated,  raised  above  the  hinge-line. 
Interior. — There  are  three  pit-like  muscle-scars  anteriorly,  as  in 
the  preceding  species ;  but  I  have  not  ascertained  the  position  of 
the  posterior  muscle. 
Size. — Antero-posterior  measurement,  13  mm.  (£  inch)  :  dorso- 
ventral,  12  mm.  (T7^  inch) ;  from  side  to  side,  11  mm.  (|  inch). 
Localities. — Shale  above  the  Brown  stone  portion  of  the  Bo’ness 
Lower  Ironstone,  Edge  Coal  Series  ;  Hard  Mine,  Dividy  Lane, 
Longton. 
Remarks. — Mr.  R.  Etheridge,  Jun.,  observes  that  the  convexity 
of  shell  distinguishes  this  species  from  A.  triangularis  ;  the  more 
prominently  developed  anterior  end,  the  median  position  of  the 
diagonal  ridge,  and  its  more  direct  course,  from  A.  carinata  and 
A.  quaclrata.  I  have  adhered  in  greater  part  to  his  own  description. 
Two  specimens  at  Jermyn  Street,  described  as  Anthracoptera 
Sowerbyi  (Etheridge,  MSS.),  are  probably  of  this  species. 
Anthracoptera  obesa. 
R.  Etheridge,  Jun.,  Quart.  Journ.  Geol.  Soc.  vol.  xxxiv.  (1878)  pp.  12-13, 
pi.  i.  figs.  12,  13  (&  14  ?). 
11  Sp.  Char. — Trigonal,  very  gibbous,  inequality  of  the  valves 
•distinctly  marked  ;  anterior  side  pointed,  well  marked,  and  defined 
by  the  byssal  furrow  in  each  valve  ;  posterior  side  but  littlejlattened, 
