Yol.  49. J  PROM  THE  DISTRICT  OF  GTRVAN,  AYRSHIRE.  307 
Fig.  6.  Primitia  elongata,  Krause,  var.  nuda ,  nov.  Eight  valve. 
Figs.  7-9.  Primitia  girvanmsis,  sp.  nov.  Fig.  7,  hollow  cast  of  right  valve ; 
8,  hollow  cast  of  left  valve  ;  9,  right  valve. 
Fig.  10.  Primitia  Grayee,  sp.  nov.  Left  valve. 
Fig.  11,  Primitia  mundula,  Jones,  var .fimbriata,  nov.  Eight  valve. 
Figs.  12-15.  Primitia  mundula ,  Jones,  var.  Klcedeniana,  nov.  Figs.  13  &  14. 
Left  valves  ;  Fig.  15.  Eight  valve. 
Plate  XIY. 
Fig.  1.  Primitia  TJlrichiana ,  sp.  nov.  Left  valve. 
Fig.  2.  Beyrichia  Kloedeni,  M‘Coy,  var.  infecta ,  nov.  Eight  valve. 
Figs.  3  &  4.  Beyrichia  Kloedeni,  M'Coy.  Varieties.  Fig.  3.  Eight  valve,  with 
the  front  lobe  modified  ;  Fig.  4.  Eight  valve,  broadly  margined. 
Fig.  5.  Beyrichia  imjpar,  sp.  nov.  Eight  valve. 
Fig.  6.  Ulrichia,  sp.  ?  Eight  ?  valve. 
Fig.  7.  Primitia  Krausei,  sp.  nov.  Eight  valve. 
Fig.  8.  Ulrichia  girvanensis,  sp.  nov.  Left  valve. 
Fig.  9.  Ulrichia  Grayee ,  sp.  nov.  Eight  valve. 
Figs.  10  &  11.  Sulcuna  preecurrens,  sp.  nov.  Fig.  10.  Left  valve  ;  Fig.  11. 
Eight  valve. 
Fig.  12.  Cypridina  Grayee ,  sp.  nov.  Left  valve. 
Discussion  (ox  THE  TWO  PRECEDIXG  PAPERS). 
The  President  said  that  it  was  a  great  advantage  to  have  de¬ 
scriptions  of  these  small  organisms  from  such  an  expert  as  Prof. 
Jones.  In  tenui  labor,  at  tenuis  non  gloria.  The  Author,  like 
specialists  in  other  groups,  was  finding  that  the  forms  ran  into  each 
other  and  that  difficulties  in  nomenclature  arose  in  consequence. 
Mr.  Marr  stated  that  Prof,  Hicholson  and  he  were  greatly 
indebted  to  the  Author  for  the  trouble  he  had  taken  in  studying 
these  obscure  fossils  from  the  rocks  of  the  Cross  Fell  Inlier.  He 
asked  whether  any  assurance  could  be  given  of  the  restriction  of 
some  of  these  fossils  to  definite  zones. 
The  Author,  in  reply  to  the  previous  speaker's  inquiry  as  to  the 
zonal  occurrences  of  these  Palaeozoic  Ostracoda,  could  refer  to  his 
Table  of  the  Eange  of  the  Genera  in  the  Quart.  Journ.  Geol.  Soc. 
vol.  xlvi.  (1890)  pp.  3—5,  to  which  Sulcuna  and  Cypridina  would  now 
have  to  be  added,  both  reaching  to  the  Carboniferous.  Speaking  as 
to  the  stratigraphical  value  of  the  species,  he  said  that  some  are  very 
characteristic  of  certain  stratal  groups — as,  for  instance,  Primitia 
strangulata ,  Beyrichia  complicatci ,  etc.,  of  some  Lower-Silurian  beds  ; 
Leper ditia  balthica,  etc.,  of  the  L  pper  :  Entomis  striato-striata  of 
Devonian  ;  and  Carbonict  fabulina  of  the  Coal-measures.  He  would 
not  trouble  them  with  definitions  of  character, — many  forms  were 
distinguished  with  difficulty,  and  we  had  to  rely  on  small  differences 
in  the  carapace-valves,  indicating  probably  considerable  differences  in 
the  limbs  and  soft  parts  within  the  test. 
