Vol.  49.] 
FROM  THE  DISTRICT  OF  GIRVAN,  AYRSHIRE. 
299 
is  more  fully  curved  than  the  other  (fig.  9).  The  free  margin  has  a 
flattened  rim.  The  sulcus  is  wide  at  the  top,  and  bordered  ante¬ 
riorly  by  an  incipient  lobe.  The  surface  is  punctate.  Fig.  9  retains 
some  shell. 
Primitia  bursa ,  Krause  (Zeitschr.  Deutsch.  geol.  Gesellsch.  1889, 
p.  9,  pi.  i.  figs.  7-10),  is  a  simple  form  with  a  thickening  of  the  edge 
of  the  sulcus,  especially  in  front,  and  is  a  near  relative  to  the  above. 
In  the  Girvan  form  here  noticed  there  is  the  difference  of  a  flattening 
along  the  border,  a  wider  sulcus,  and  the  rounded  thickening  at  its 
front  edge.  The  imperfect  lobe  and  its  sulci  are  not  so  far  advanced 
as,  although  evidently  prototypical  of,  Beyrichia  arcuata 1  (Bean). 
Not  knowing,  we  ma}'  regard  it  as  a  new  species,  girvanensis. 
Figs.  7  &  8  in  no.  114,  and  fig.  9  in  115,  both  grey  shale. 
4.  Primitia  Grayee,  sp.  nov.  (PI.  XIII.  fig.  10.) 
Size. — Length  *6,  height  *4  millim. 
This  small  semi-oval  or  bean-shaped  Primitia ,  with  the  front 
margin  of  its  sulcus  much  thickened,  and  the  surface  pitted,  appears 
to  be  different  from  any  at  present  published  ;  and  it  may  well  be 
distinguished  by  naming  it  in  honour  of  Mrs.  Gray,  the  discoverer 
of  this  and  many  other  fossils  in  the  Girvan  district,  to  which  she 
has  devoted  careful  attention  for  several  years. 
With  a  film  of  shell.  In  no.  120,  grey  shale. 
5.  Primitia  mttndela,  Jones,  var.  fimbriata,  nov.  (PI.  XIII. 
fig.  11.) 
Size. — Length  (without  the  border)  1*52,  height  f'0  millim. 
Among  the  series  of  Lower- Devonian  varieties  of  P.  munclula 
described  and  figured  in  the  Ann.  Mag.  Nat.  Hist.  ser.  6,  vol.  iii. 
1889,  pp.  375-377,  pi.  xvi.,  there  are  two  in  particular  (figs.  6  &  9), 
which  approximate  closely  to  our  fig.  11  in  the  form  and  sulcus,  and 
would  probably  have  quite  the  same  shape,  but  the  latter  is  slightly 
imperfect  at  the  antero-dorsal  border.  There  is,  however,  a  dis¬ 
tinctive  feature  in  the  broad  border  and  prickly  posterior  margin 
of  fig.  11;  but  these  need  not  separate  it  specifically,  and  we  may 
regard  it  as  var  .fimbriata. 
P.  mundula  has  a  long  and  wide  range  as  a  species  with  many 
xariations.  Dr.  Krause  figures  and  describes  some  good  Upper- 
Silurian  forms  in  the  Zeitschr.  Deutsch.  geol.  Gesellsch.  vol.  xliii. 
1891,  p.  495,  pi.  xxx.  figs.  5-7. 
In  no.  118,  grey  shale. 
•r 
6.  Primitia  mtjndttla,  Jones,  var.  Klcedeniana,  nov.  (PI.  XIII. 
figs.  12,  13,  14,  &  15.) 
Size. — Fig.  12  :  Length  1*0  ,  height  -48  millim. 
Fig.  13  :  Length  1*04,  height  -48  millim. 
Fig.  14  :  Length  1-04,  height  *52  millim. 
Fig.  15  :  Length  1*2  ,  height  *56  millim. 
1  Ann.  Mag.  Nat.  Hist.  ser.  6,  vol.  iii.  1889,  p.  381,  pi.  xvii.  fig.  7. 
x  2 
