Eight  teeth  of  the  row,  c,  next  in  advance  are  preserved  on  the  left
side  of  the  jaw  :  they  diminish  in  greater  degree,  in  size,  than  do  tliose
of  the  row  h  compared  with  a ;  they  rise  higher  and  more  abruptly
at  the  middle  of  the  crown  ;  the  anterior  end  is  more  contracted ;  the
inferiority  of  size  of  the  innermost  as  compared  with  the  rest  is  greater.
A  low  ridge  is  continued  from  the  summit  of  the  crown  to  the  ends  of
the  tooth,  that  to  the  fore  end  being  more  marked  than  the  one  behind,
and  the  anterior  ridges  are  more  prominent  in  the  outer  teeth  of  the
row,  r.  r>,  6,  7,  than  in  the  inner  teeth,  1-4.  The  length  of  the  work-
ing Ruiface  of  the  fourth  tooth,  c,  4,  is  0028  m.  m. ;  the  breadth  is
0011  m.m.
^  As  fthowD,  in  section,  magnified,  in  plate  zz.  of  m j  '  Odontograph j.*


Frof.  Owen — On  a  Jaw  of  StmphoiM.  195

fii^it  taetfa  of  the  foiemott  or  sympbyrial  row  of  teeth,  il,  are  pre-
■erred  on  the  left  ride.  The  ezpoeed  parts  of  the  working  rarnoe
augment!  from  0-008  m.  m. — ^the  longitudinal  diameter  of  ue  inner-
most, 4»  to  0*020  m.m.  that  of  the  sixth  tooth  in  advanoe.  Hie  d^pnea
of  conTezity  of  the  grinding  sorfaoe  increases  from  the  innermost  to
the  fourth ;  in  advanoe  of  tiiis,  the  ganoin  ooating  has  been  more  or
less  broken  away;  in  the  fifth  and  rizth  teeth,  tiie  ridge  oontinued
firom  the  oonvexity  to  the  ends  of  the  teeth  becomes  marked,  and
more  strongly  as  die  tooth  advances  in  position.  The  right  and  left
teeth  of  this  foremost  series  are  alternate,  and  loosely  interlock  at  the
mid-line  of  the  symphysis.
