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PROF.  T.  R.  JONES  ON  SOME  PALiEOZOIC  [Aug.  1 893, 
These  are  much  longer  and  more  scaphoid  forms  than  fig.  4, 
being  narrower  and  produced  anteriorly,  with  a  long  elliptically- 
curved  antero-ventral  border.  Pig.  6  shows  a  faint  continuation  of 
the  sulcus  downwards. 
Localities. — Pig.  5  :  In  dark-grey  schistose  mudstone ;  from  the 
Staurocephalus-limestone  Series  at  Billy  Beck.  Pig.  6  :  In  a  crushed 
limestone  of  the  Staurocephalus- limestone  Series  from  Swindale. 
II.  Genus  Aparchites,  Jones,  1889. 
1.  Aparchites  subovatus,  sp.  nov.  et  var.  (PI.  XII.  figs.  7  & 
8  a ,  6,  c .) 
Size. — Pig.  7  :  Length  1*4  millim. 
Pig.  8 :  Length  *7 6  millim.,  height  *4  millim.,  thickness 
•28  millim. 
In  form  like  Primitia  minuta,  treated  of  in  Quart.  Journ.  Geol. 
Soc.  vol.  xlvi.  1890,  pp.  7-9,  pi.  iii.  figs.  18,  19,  21-23 ;  but,  not 
showing  any  signs  of  a  dorsal  furrow,  nor  associated  with  similar 
forms  having  that  sulcus,  they  stand  as  Aparchites. 
Specimens  of  nearly  the  same  outline  and  features  occur  in  the 
Lower- Silurian  strata  of  the  Girvan  district,  and  are  termed  A. 
subovatus  in  the  descriptive  notes  ou  those  Ostracoda,  hereafter 
following  (p.  297). 
Pigs.  7,  8  appear  to  be  varieties  of  one  form  ;  although  possibly, 
if  we  had  better  material  to  study,  they  might  be  found  to  be  quite 
distinct.  Pig.  7  (a  left-hand  valve)  is  narrowed  and  subacuminate 
anteriorly  (having  approximately  the  outline  of  fig.  5  a).  Pig.  8 
(left  valve)  is  much  shorter  than  fig.  7,  fuller  in  the  ventral  curve  of 
its  anterior  moiety,  and  has  preserved  a  punctate  surface ;  the 
others  are  more  or  less  decayed  on  the  surface. 
Localities.- — Pig.  7  :  In  greenish-grey  schistose  mudstone ;  from 
the  StauroceplialusAxme&konQ  Series  at  Billy  Beck.  Pig.  8  :  “  Dufton.” 
2.  Aparchites  stjbtruncatus,  sp.  nov.  (PI.  XII.  figs.  9  a ,  6,  c.) 
Size. — Length  1*04  millim.,  height  *46  millim.,  thickness  *28 
millim. 
Pig.  9  (right  valve)  is  blunter  in  front  than  fig.  7,  and  more  evenly 
curved  below  than  figs.  7  and  8,  and  it  has  a  postero-dorsal  slope. 
Locality. — “  Pusgill.” 
3.  Aparchites  leperditioides,  sp.  nov.  (PI.  XII.  figs.  10  a,  6,  c.) 
Size. — Length  *8  millim.,  height  *44  millim.,  thickness  *24  millim. 
This  has  a  decidedly  Leperditia- like  outline,  such  as  gives  cause 
also  to  the  name  A.  leperditioides  among  the  Girvan  specimens 
(see  p.  296).  It  has  here  a  punctate  surface. 
Locality. — “  Pusgill.” 
III.  Genus  Cytherella,  Jones  &  Bosquet,  1848-52. 
[Por  a  synopsis  of  the  Cytlierellce ,  see  Monogr.  Carbonif.  Cypridin. 
Pal.  Soc.  1884,  pp.  58-69 ;  also  Ann.  Mag.  Nat.  Hist.  ser.  5, 
vol.  xix.  1887,  p.  192,  for  a  Silurian  species.] 
