264  DE.  WHEELTON  HIND  ON  THE  AFFINITIES  OF  [May  1 893, 
of  mottled  marls  above  the  [Spirorbis-'}  limestones,  in  the  Black  Bass 
or  shale  above  the  Main  Limestone,  and  in  the  shale  beneath  all  the 
calcareous  bands.’* 
Of  these  four,  I  suspect  the  last  is  the  shell  figured  by  Salter, 
Quart.  Journ.  Geol.  Soc.  vol.  xix.  (1863),  as  Naiadites  Icevis,  and 
referred  to  by  Prof.  T.  Rupert  Jones,  Geol.  Mag.  for  1870,  pi.  ix. 
fig.  15,  p.  220  ;  but  I  refer  again  to  this  under  A.  scoticci. 
The  2nd  and  3rd  are  probably  different  forms  of  the  shell  under 
description,  which  does  vary  in  shape  as  described. 
I  am  indebted  to  the  Curators  of  the  Owens  College  Museum  for 
the  loan  of  Prof.  Williamson’s  type-specimen,  and  for  permission 
to  figure  it. 
Localities. — In  the  blackbands,  ironstones,  and  shales  of  the  Worth 
Staffordshire  Coalfield,  as  far  down  as  the  Bassy  Mine ;  in  the  Knowles 
Ironstone ;  Upper  Coal  Measures  of  the  Lancashire  Coalfield : 
Ardwick;  Coal  Measures,  Bradford  ;  Blackband,  South  Wales. 
Antheacomya  scotica.  (PI.  X.  fig.  31.) 
R.  Etheridge,  Jun.,  Geol.  Mag.  for  1877,  ph  xii.  fig.  8,  pp.  244,  246. 
Specific  Characters  (Etheridge).— “  Obliquely-broad-ovate,  flat¬ 
tened,  abruptly  truncated  along  the  dorsal  margin.  Anterior  end 
rounded  ;  posterior  end  produced  ventrally,  its  margin  obliquely 
rounded.  Hinge-line  not  so  long  as  the  shell,  passing  insensibly 
into  the  oblique  posterior  margin.  Umbones  anterior,  but  not  ter¬ 
minal,  inconspicuous.  Shell  marked  with  exceedingly  close,  fine, 
microscopic  thread-like  striae,  with  a  few  transverse  wrinkles,  which 
at  times  give  it  the  appearance  of  being  partially  radiately  striated.” 
Remarks. — Mr.  R.  Etheridge,  Jun.,  thinks  this  form  closely 
resembles  Naiadites  Icevis  (Dawson),  though  the  latter  is  much 
smaller,  and  the  concentric  striae  closer,  finer,  and  more  numerous ; 
the  posterior  end  is  more  obliquely  truncated,  and  the  beaks  more 
anterior.  Salter,  Quart.  Journ.  Geol.  Soc.  vol.  xix.  ( L863)  p.  80, 
identifies  Sir  J.  W.  Dawson’s  shell  with  one  found  in  the  Upper 
Coal  Measures  of  Manchester.  Dawson’s  shell  was  in  1870,  by 
Prof.  T.  Rupert  Jones,  Geol.  Mag.  pi.  ix.  fig.  15,  Appendix,  p.  220, 
described  as  an  Estheria,  and  p.  218,  the  fragment  of  a  similar  shell 
is  mentioned  from  the  Ardwick  beds ;  but  in  1877  the  same  writer 
is  quoted  by  R.  Etheridge,  Jun.,  in  the  paper  from  which  I  take  the 
latter’s  description  of  the  shell  under  discussion,  as  having  inde¬ 
pendently  referred  the  Scottish  fossil  to  Sir  J.  W.  Dawson’s  species. 
I  figure  a  pretty  little  shell  found  in  the  Ardwick  Limestone, 
which  may  belong  to  the  form  in  question,  but  I  cannot  venture  to 
pronounce  on  the  point  until  I  have  been  able  to  obtain  specimens 
of  the  Scottish  and  American  species  for  study  and  comparison. 
Mr.  Etheridge  (op.  cit.  p.  245)  suggests  that  Hibbert’s  U.  nuciformis , 
from  the  Burdiehouse  Limestone,  is  an  uncrushed  example  of 
A.  scotica ,  a  particularly  convex  and  globose  form,  but  unfortunately 
Hibbert’s  specimen  has  entirely  disappeared. 
Localities. — Cement-stone  Group,  Burdiehouse  Limestone ;  Binn 
