298  PROF.  T.  R.  JONES  ON  PALJEOZOIC  OSTRACODA  [Aug.  1 893, 
occasionally  among  local  groups  individuals  bore  evidence  of  the 
sulcus  or  of  a  slight  dorsal  depression. 
Among  the  Girvan  collection  similar,  but  quite  non-sulcate,  forms 
exist,  and  there  appears  to  be  no  valid  reason  for  placing  them  with 
Primitia ;  they  should  therefore  be  systematically  grouped  under 
Ajoarchites ,  together  with  figs.  1,  2,  &  3.  Pig.  4,  indeed,  may 
be  said  to  be  an  elongated  modification  of  fig.  1,  so  far  as  the 
outline  is  concerned ;  and  fig.  5  is  a  larger  and  more  symmetrical 
subovate  form,  like  some  examples  of  Primitia  minuta  above- 
mentioned.  Neither  here  nor  in  the  Westmoreland  district,  where 
similar  specimens  are  found  (see  above,  p.  292),  are  there  evidences 
of  the  Primitian  sulcus  or  pit,  which  is  required  for  the  division  of 
that  genus  from  Aparchites. 
Pig.  4  in  no.  115,  grey  shale  ;  fig.  5  in  no.  117,  hard  greenish 
shale.  Thin  films  of  decayed  shell  remain. 
II.  Genus  Primitia,  Jones  &  Holl,  1865. 
1.  Primitia  elongata,  Krause,  var.  nuda,  nov.  (PI.  XIII.  fig.  6.) 
Zeitschr.  Deutsch.  geol.  Gesellsch.  1891,  p.  494,  pi.  xxx.  fig.  4. 
Size. — Length  *88,  height  *4  millim. 
Except  in  having  a  smaller  sulcus  and  no  punctation,  fig.  6  agrees 
with  Dr.  Krause’s  P.  elongata  referred  to  above,  from  the  Lower- 
Silurian  Beyrichien-Kalk  of  Scandinavia.  Its  outline  has  just  the 
same  elongate  dorsal,  and  very  slightly  curved,  parallel  ventral 
border,  and  nearly  equal  truncate  ends,  curved  below,  but  meeting 
the  dorsal  edge  with  strong  angles.  At  most  the  difference  in 
sulcus  and  pitting  can  make  it  a  variety,  nuda. 
This  neat  sub-oblong  form  of  Primitia  is  not  common ;  but  it  has 
allies  among  the  varieties  of  P.  valida,  J.  &  H.,  and  of  P.  humilis , 
J.  &H. 
In  no.  116,  grey  shale. 
2.  Primitia  Krausei,  sp.  nov.  (PI.  XIV.  fig.  7.) 
Size. — Length  *52,  height  ’36  millim. 
Sub-oblong,  elongate,  compressed  anteriorly.  Pront  end  subtrun¬ 
cate  ;  posterior  elliptically  rounded.  Sulcus  short,  but  distinct. 
Surface  punctate  (?).  Differs  from  fig.  10,  PI.  XIII.,  in  its  narrower 
and  more  oblong  form,  and  in  its  compressed  anterior  moiety.  A 
thin  film  of  shell  shows  faint  pitting. 
This  new  species,  P.  Krausei ,  is  named  after  Aurel  Krause,  of 
Berlin,  an  enthusiastic  worker  among  the  Scandinavian  Ostracoda 
found  in  the  Drift  of  North  Germany. 
Is  in  no.  116,  grey  shale. 
3.  Primitia  girvanensis,  sp.  nov.  (PL  XIII.  figs.  7,  8,  &  9.) 
Size. — Pig.  7  :  Length  *84,  height  *6  millim. 
Pig.  8  :  Length  *96,  height  *68  millim. 
Pig.  9  :  Length  1*16,  height  *76  millim. 
The  dorsal  edge  is  straight,  the  ventral  elliptical ;  the  hinder  end 
