356 
cT  Length  about  60  mm.;  width  of  10**  8.5;  of  Is*  5;  length 
of  1*  3. 
Ç  (young  with  18  somites).  Length  27,  width  of  10th  5.7,  of  1st  3.5, 
length  of  Is*  1.7. 
51.  Platyrhachus  bidens,  sp.  n.  Pl.  XXI,  fig.  2  — 2b. 
Sumatra:  Paningahan. 
Colour  black,  the  tips  of  the  carinal  processes  only  being  white; 
legs  ochraceous  proximally. 
Head  granular  above,  with  frontal-sulcus. 
Antennœ  long,  a  little  more  than  twice  the  length  of  the  head, 
the  segments  subequal  in  length. 
The  first  tergite  with  a  deep  furrow  before  the  anterior  border  and 
a  row  of  round  tubercles  along  it,  its  surface  nearly  flat  and  granu- 
lar; its  keels  well  developed,  directed  obliquely  upwards  and  back- 
wards ,  subcylindrical ,  stouter  at  the  base  than  at  the  apex.  The  keels 
of  the  second;  third  and  fourth  segments  alike  in  character,  rod- 
like, about  twice  as  wide  as  long,  the  anterior  and  posterior  margins 
sub-parallel,  the  lateral  margin  distinctly  bifid,  inclined  obliquely  up- 
wards. The  rest  of  the  keels  also  alike ,  inclined  upwards  and  outwards 
and,  from  about  the  10th  somite,  slightly  backwards,  a  little  wider 
than  long  or  towards  the  posterior  end  of  the  body  about  as  wide 
as  long,  the  anterior  and  posterior  margins  sub-parallel,  the  lateral 
margin  very  deeply  emarginate,  each  of  the  two  lateral  angles  taking 
the  form  of  a  long  and  strong  tapering  tooth;  the  keel  of  the  19th 
somite  not  only  small,  not  bidentate.  The  dorsal  surface  dull,  not 
quite  smooth,  with  a  row  of  tubercles  along  the  hind  margin  of 
each  somite.  Pores  situated  at  the  base  of  the  posterior  side  of  the 
anterior  projection  of  the  keels.  Sides  of  the  somites,  finely  granular. 
Sterna  not  spined,  although  with  a  low  tubercle  at  the  base  of 
each  leg;  longitudinally  and  transversely  scooped  out.  Caudal  process 
squared,  with  parallel  sides,  very  lightly  convex,  sublobate  posterior 
border. 
Legs  normally  formed. 
Copulatory  foot  slender,  lightly  curved,  terminating  in  two  sub- 
equal  slender  processes  which  are  curved  upwards  and  backwards,  the 
superior  being  a  little  shorter  and  a  little  more  curved  than  the 
inferior. 
