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PEOE.  T.  E.  JONES  ON  PAL2EOZOIC  OSTEACODA  [Aug.  1893^ 
25.  On  some  Paljeozoic  Osteacoda  from  the  Disteict  of  Gievan, 
Ayeshiee.  By  Prof.  T.  Rupeet  Jones,  F.R.S.,  F.G.S.  (Read 
April  12th,  1893.) 
[Plates  XIII.  &  XIV.] 
Contents. 
§1.  Introduction . . . 
§  2.  Description  of  the  Species  and  Varieties  . 
§3.  List  of  the  Fossil  Entomostraca  from  the  Girvan  District .. 
(а)  Those  mentioned  in  Nicholson  and  Etheridge’s  Mono 
graph . 
(б)  Those  from  the  Whitehouse-Bay  Shales . 
(<?)  Those  from  Bargany-Pond  Burn..,. . 
§  1.  Inteodection. 
This  paper  aims  at  the  completion  of  the  palaeontological  account 
of  the  Girvan  district,  so  far  as  the  Ostracoda  are  concerned ;  and 
follows  up  the  researches  indicated  in  the  ‘  Monograph  of  the 
Silurian  Fossils  of  the  Girvan  District  in  Ayrshire,’  by  Nicholson 
and  Etheridge,  Jun.,  vol.  i.  1880. 
In  about  a  dozen  pieces  of  the  fossiliferous  shales,  submitted  for 
examination  some  few  years  ago,  the  writer  finds  nearly  thirty  spe¬ 
cimens  (chiefly  casts)  of  Primitia ,  Beyrichia ,  Ulrichia,  Sulcuna ,  and 
Cyjpridina,  which  show  interesting  gradations  of  form,  not  always 
easy  to  be  defined  as  specific  or  even  varietal,  but  valuable  as  illus¬ 
trating  modifications  during  the  life-history  of  individuals,  thus  often 
leading  to  permanent  characteristics  of  species  and  genera.  Like 
those  formerly  described  in  Nicholson  and  Etheridge’s  ‘  Monograph,’ 
the  specimens  have  all  been  collected  by  Mrs.  Elizabeth  Gray  of 
Edinburgh. 
Excepting  a  small  cast  of  a  Beyrichia  Kloedeni ,  M‘Coy,  B.  Kloedeni, 
var.  scotica,  Jones  &  Holl,  a,nd  Ulrichia  Grayce ,  Jones,  which  are 
of  Llandovery  age,  from  the  Burn  leading  to  Bargany  Pond,  all  the 
specimens  here  described  are  from  the  dark-grey  Lower-Silurian 
(Middle-Bala)  shales  of  Whitehouse  Bay.  See  Dr.  C.  Lapworth’s 
Memoir  on  6  The  Girvan  Succession,’  Quart.  Journ.  Geol.  Soc. 
vol.  xxxviii.  1882,  pi.  xxv.  fig.  3  (map);  fig.  16  at  p.  595;  and 
pp.  597,  603,  606,  612,  621,  and  661. 
The  numbers  attached  to  Mrs.  Gray’s  little  hand-specimens  are 
here  inserted,  together  with  the  character  of  the  shale  in  which  the 
Ostracoda  occur,  for  each  species. 
§  2.  Desceiption  oe  the  Species  and  Vaeieties. 
I.  Genus  Apaechites,1  Jones. 
1.  Apaechites  lepeeditioides,  Jones.  Seethe  preceding  paper, 
p.  292,  PI.  xii.  fig.  10.  (PI.  XIII.  figs.  1,  2,  &  3.) 
1  Ann.  Mag.  Nat.  Hist.  ser.  6,  vol.  iii.  1889,  p.  384. 
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